just to clarify my thoughts on that part: these discussions have been going on for a while. wrc has two manufacturers participating. during all the meetings to decide whats next, one of these 2 brands start to say around that they may leave depending on what direction the rules goes (because they know where the decisions are heading, they are on the meetings). if they didnt cared about losing hyundai to define this set of rules is probably because there was more people om this table agreeing with them. not saying new manufacturers per se, but at least other teams, for sure. otherwise they'd keep some efforts to please hyundai too, like they did when they cancelled the ditching of hybrid at that first time.
does that make sense? im thinking more of some wrc2/erc/middle-east teams thinking "yep, we can enter rally1 with these cheaper cars", not actual factory teams.