While this is a good article, and a lot of the points are pretty accruate, only two things matter:
1. Fundamentally good faction design
2. Frequent patching
CoH3's success, or really any MP-focused game, is based entirely on its ability to keep an active player base; and that's something you can't rebuild after a few years (unless you're incredible lucky). That means the game needs to be released in a good state, and maintained with quick, iterative patches
If/When a new game comes out, the factions need to be fundamentally well designed, so they don't require a rework (or rely entirely on gimmicks). That means all the factions need access to basic tools (snares, suppression, mobile indirect fire,etc. ) and simultaneously can't rely on units with "make-or-break" abilities that take them from being awful to insanely OP (launch 'brace' ability). A large portion of the community latches on to a single faction, so if that faction is fundamentally broken OR continuously faces broken (overpowered) factions, they'll leave. This doesn't mean the game needs to be absolutely perfect on launch, but it does mean that they need to be within 5-10% of each other in terms of 'power', across most skill levels.
The second point is equally as important, since problem areas need to be addressed quickly in order to prevent people from leaving because "the game is broken". If players encounter something overpowered, gimmicky, or frustrating, they'll generally accept it for a bit - but it can't stay like that for long; this is especially important for game breaking stuff (i.e. full-auto sherman, etc.).
Those two points are critical; miss both, and we're just back in CoH2's situation where it took years for it to be "good" and even longer to get it to the current status.
And dont forget maps, like WhiteFlash already said maps are as important if not more important as faction design!
Generally i'm speaking for 2v2 maps but before last 2 patches the map pool was really terrible! Right now it's getting better also if there's still some maps where if u start on certain point u're totally in advantage ( thinking about cha'rkov south, Moskow's south) ..or some maps that there shoudn't be like Ettelbruck.
You can make the best factions design ever but without a decent map u'll not enjoy playing them