There isn't enough info for me to be concerned at all. Although I too wish Y'shtola would be sidelined in 7.0 instead of actively accompanying us if Krile is becoming a party member for the reasons you said... Enough with the abundance of Sheldon Coopers following us everywhere please, one is enough.
It'd be really nice if the next expansion gave us more fresh new expansion-long allies replacing seats from characters that are done with their MSQ development like Thancred, Urianger and Alphinaud. I'm not holding my breath that bloody UwU fanboy G'raha won't be part of the main party and Y'shtola will probably stick around if they don't have her decide she got enough to keep to her research by the end of 6.55.
Ideally, and I'd understand G'raha staying in this case, the characters that didn't join until Endwalker should stay, and new ones should be introduced, so to really cement this as a new saga in the making. But it's the merchandise appeal that will dictate the writing decisions. Those ludicrously overpriced Square-Enix figurines and statues need to appeal to whales after all.
If they add new ones I really hope they pick from the races not represented yet: Roegadyn, Viera and/or Hrothgar. And no, I don't think they should pick a job NPC.
