I believe the likelihood of EA ignoring last-gen console sales is 0%. EA is a publicly traded for-profit company after all.
Last gen consoles will probably have smaller maps and a lower frame rate of 30 FPS for the $60 base game.
The free-to-play Battle Royale build will probably have dumbed down graphics and lower system requirements compared to the $60 base game, so last gen consoles can support larger Battle Royale modes.
I'm in the same position of not managing to get a PS5 yet. But the devs did try and suggest that a lot of the problems with BFV stemmed from old consoles holding them back (I'm not entirely convinced) and a dev also posted a video on twitter that he said showed you got a more stable connection to the online game with next gen consoles. So I think they probably will go next gen only and maybe backward a stand alone firestorm or use mobile to make up any difference.
If they try and do some early access/stepped release again it may be better value to wait anyway but also if it doesn't release till year end consoles may be easier to get by then.
