So here's the characters from MKX who I believe will not be in MK11:
Mileena, Baraka, Quan Chi, Shinnok
The MKX story deaths. Their deaths were quite cinametic and I just think NRS is probably gonna want the lower bodycount to have a stronger meaning this time around, at least, for the moment.
"But MK9!" 13 characters died in MK9 pretty much, only 5 of them are playable in MKX.
Sonya, Kenshi, Jax, Johnny Cage, Kano
Their kids are probably gonna replace them fulltime, though I think it's a big possibility one or two of them might end up appearing as a DLC or something alike, namely JC and Jax.
Ermac, Reptile, Ferra/Torr
I think these guys are gonna be gone to make way for other characters to take their place as Kotal's lackeys, and to change up the roster from MKX a bit. I think Ermac's ladder ending will be canonical and pave the way for Shang Tsung's return as well.
Triborg
MK11's probably gonna have only one cyborg, in their real form, rather than the amalgamation.
Goro
Not much to say. Def not going to be the pre-order char again or a DLC, and I really don't see him being in the regular roster.
Uhh I would keep on going but this post's too long already so I'll leave it at that, those are my main picks anyhow.