I would sincerely hope they would stay away from TOS for the time being. McFarlane's biggest mistake, in my opinion, was not starting with Discovery. And NOW we've got just too many new shows/characters to go back and recycle characters we've done before...at least in looks we've seen before. I'd love to see a 6" or 7" multiverse wave one that would/could include Burnham, T'Kuvma, Picard and Narissa, with a close follow up second wave of Saru, the Ba'ul, Soji and Narek and go from there. The absolute last thing that I want is another TNG Picard or TOS Kirk. If a multiverse line does well, then maybe they can start stretching into 24th Century or TOS/Enterprise. I would love a line like that to go on forever, like the Star Wars Black Series...but it's gotta be bold enough to do some new characters upfront. Though I am curious how they'd handle Lower Decks...would they be animation accurate or would they "humanize" them to fit the other characters?
I'm sure we'll never know. But it's still fun to think about.