Profile of nee

You're not going to discourage blobbing by removing forward retreat, players will just take it in stride (har har!) and re-blob like 1-2 minutes later than usual- retreating squads run faster, after all.

Forward Retreat has its own share of drawbacks, first being placement, which itself requires securing the territory (required for OKW and UKF, but you can be very gutsy as USF), and second being securing it throughout the match, which demands micromanagement outside of blobbing.

If you want blobbing to be discouraged you can do something like implement upkeep cost when FRP is in effect, forcing players to toggle it only at the right moment to optimize economy. Or even just simply up the FRP upgrade cost. You know why you can't blob Sturmpioniers?
If you just remove FRP it won't do anything except maybe encourage it even more because FRP itself is expensive. Only Major doesn't require an upgrade for FRP but he's T4 unlock and a 3-man squad.
If that OKW blobber no longer has a 300 manpower sink, it's just going to another Volksgrenadier.

FRP itself gets in the way of blobbing. If USF is the worst of them all it's only because Major is mobile, comes regardless (ie not a side tech), has other abilities and can reinforce and heal next to ambulance. Think of all that micromanagement and manpower that can be spent in more blobbing if they simply didn't have it. It might discourage blobbing in massive maps, but most people apparently are 1v1 or 2v2, and large team game has never been the measuring stick for balance anyways.

I don't see FRP is the problem, and I think frustrated people are just pointing fingers looking for a reason convinced it is and if only it's gone.

For myself I love forward retreat, but I'm largely a big map player where having an FRP close to the middle and kept secure is a major tactical focus. I would accept an increase or even upkeep/ population cost for FRP upgrade. If you want to discourage blobbing there should be more or more expensive manpower choices for the player to sink into which accomplishes tactical decisions while also requiring less manpower for blobs. In an example of increasing 300 manpower to 400 manpower for FRP for OKW, it's still worth it but obviously makes both the investment into FRP as well as blobbing harder to achieve. You don't even need to do fancy things like removing medics or making it come later, all which demand deeper balance examination. If FRP is such an important tactical option, it should also cost; it already does at the tactical level but not so much at the economy side; ultimately 300 manpower isn't a lot for OKW.

Maybe add a salvage option to emplacements? Terrans in Starcraft 2 can do this with turrets and bunkers (in some game modes, anyways). Recoup only a percentage of cost, and maybe also relative to current health? ie you only get like 5% back if it's about to die, whereas full health it will give back like 50-70%

Veterancy can be ignored so you will be incentivized to place them strategically and not constantly salvage.

This might require something like a cap for emplacements, so that you don't leapfrog them over the length of a map. Which of coures makes the idea more complicated.

I think I recall double tapping an issue with some other units, like HVAP. I also recall they were fixed, so it'd be merely a matter of applying the same to JT.

I don't hate the idea of weapon racks, but it's hardly a perfect idea. UKF has the benefit of construction Forward Assembly, of which weapon racks are just one benefit among several.
If I am reading OP right s/he is merely saying that units in HQ sectors can upgrade the weapons, so the "retreat back to base" still applies, but without the micromanagement restrictions of going to a specific point in the map. You can always bring back timing for upgrades to compensate for what is ultimately a buff to USF.

I think it's possible to ADD to weapon racks idea as an alternative, similar to UKF's design, without having to remove it altogether; really, the problem of weapon racks is largely about their limitations.

A few ideas:
-Ambulance can be upgraded to be mobile rack; replaces healing and reinforcement; cheap cost for ambulance and upgrade means you can build multiple ones, so you can even make it where you have to have one rack type per each truck, and variety of options for the player BARs in the field and bazooka at the base or vice versa)
-Fighting Position can be upgrade to provide ONE weapon rack; gives FPs a reason to exist; if you want to upgrades all three types you need three FPs built and upgraded to the variant(s) you want
-commander abilities allow you to air drop the weapons for a slightly higher munitions cost
-call-in racks (ie supply glider), or simply the USF version of British supply halftrack, which requires unlocking racks before you can drop weapons, but has the inherent benefit of reinforce and transport

Really, there are multiple creative ways to implement "forward racks" without simply removing the base racks idea.

To be realistic though, this is really only a big deal in the early part of the game where you might have delayed unlocking the racks, whereas a lot of later-game units like Paratroopers and Rangers have their own special unit upgrades to begin with. I mean once you've unlocked the racks, the only time you need to pay attention to getting stuff is when you actually have squads with available slots, either because you just trained them or you really need that Bazooka to deal with tanks.

Churchill is also behind tech...though it's negated by not having a limit, and a range of other benefits. Also, Comet.

If Sturmtiger is too powerful for its cost you merely up the cost or adjust it's effectiveness. Hell that's been the other steady thing about OKW nerf. Dumbest thing to do is limit it and make it exclusive with KT. That's just limiting strategic options more than resource constraints, and actually justify making the Sturmtiger more powerful. It is also lazy.