Cross play will never happen until all platform is on the exact same build which means DE will need to stopped using the PC as an update test bed; which has been the core way of how warframe is being developed. You can't crossplay between different platforms that are on a separate build perpetually.
Cross save will never happened due to platinum economy such as platinum discounts on PC but not on consoles and different trade economy within each platform. If you can buy something on one platform for 10p and sell it on another for 50p, this throws shit off.
All solvable and done by other studios and games before. Fortnight shares the ingame earned V-bucks currency between PC, XBox, Switch & Mobile. Purchased currency stays on the platform (according to the responses I googled). That way, whatever "platform tax" the respective platform holder enforces continues to work. Purchased non currency items should be available everywhere.
Out of sync builds: Elite Dangerous also transitioned from PC first builds to synchronous update releases. PC serves as beta testbed. Here it's especially irritating that any form of cross play and unified account is missing, due to the grind heavy nature of the game.
War Thunder is furthest of the games I mentioned above. Cross play between PC and XBox as well as PC and PS4 is available, naturally the clients are in sync. Only the unified account isn't, which again, due to the grindy nature, "soft" locks people to one platform.
You're right though, with the mindset of "never going to happen" it's never going to happen. Most players will probabaly never notice or care and some very special, angstful PC players will probably applaud this, since they somehow can continue to entertain the idea that their master race platform is the center of the gaming world, at least for their game. But for me personally, the lack of these features is tangibly putting me off touching the game, because of the constellation I described above. And it stands to reason that as a studio, the devs of these games might maybe (!) benefit, if they didn't lock players onto a platform or forced them to progress separate accounts, but gave them free choice of the platform with unified account progress and also: free choice with whom to play with without forcing them into a specific gaming eco system.
It's a "Game as a Service". I cannot imagine that it's easier to maintain 4 separate services than one on different platforms, once every client has been synched and accounts have been unified.
TL;DR: Where there's a will, there's a way. Precedences exist and I feel with the rise of GaaS, they'll become more and more prevalent. I'd love if Warframe became one of them.
