It doesn't nessesairly mean pay2win needs to be implemented, but mechanics dettering free players/slowing them down/putting them behind paying customers are complete MANDATORY for F2P to work.
And then there's TF2 with hats.
But on a serious note, CoH2 is on a decline. New RTS games are coming out and there won't be any big new content for the game (expect for community made skins and maps maybe). It's hard to get money out of this game right now. And as it was said, the servers and the support is not a charity.
Making quarter of the game F2P, and charging for the other 3/4 would be a working idea.
(someone had an idea making the 2 base factions free. That would be a start)
But to be honest this whole post is just a "What if.." thinking. This game won't be a F2P game, that's for certain.