So my thing with that is
-players who want to play ranked will do so regardless of guaranteed full lobbies, just as long as whoever wants to be playing ranked can do so. It's not about lobby size it's about the grind for rank.
That all said I do think they will be full anywhere. Last time with what ranked did to pubs it seems pretty clear the demand was out there 😀
-The players who will switch to ranked are the exact players that will won't be missed in squads. One of the most common complaints is that every squads lobby has that three stacked squad of "sweats" aka players who really play the game, and there is nothing wrong with that. But that squad (or two) runs over everyone. Not that lobbies are necessarily full of them. There's just "one in every lobby."
Those are the exact squads who would play ranked and in a sense are already playing "ranked," just in pubs, because that's as close as it gets for now.
Last time there was ranked it made "sweats" play a lot, and play the meta way harder.
This in turn drove the casuals out because in part it turns out the meta wasn't super fun necessarily
This proves that
-If ranked, sweats will play more (definitely proven)
-Maybe if sweats are playing ranked instead ,pubs might get busier? Since last time, with sweats playing more, and playing more to the meta, casuals played less. This means it's perhaps likely that the opposite is true and if sweats play less (ie they are off in ranked) casuals might play more?