If Inter can find someone who can pay good money for Vecino this winter, he is as good as gone. And I don't think anyone at FIF will shed a tear.
Sanchez, Eriksen and Vidal are also gone as soon as Inter can get rid of them - I guess that has more to do with wage bill and their fitness.
I am sure Kolarov and Ranocchia are also on the exit list for next summer.
If the above 4 are gone by next summer, Inter will replace some of them. My guess is that a young striker will replace Sanchez (Marotta likes Scamacca, though not sure if we will be able to afford him by next summer). And the 3 mids will probably be replaced by 1 young midfielder (Frattesi?). If the 2 CBs are also gone, they will probably be replaced by a loan returnee (Vanduesden?) and maybe Bremer.
Perisic & Brozovic are two players Inter will probably try hard to retain. If Perisic leaves, then surely he will be replaced. Ditto Brozo, tho I think we will struggle to replace him adequately hence his renewal is critical.
We will also probably get a GK sometime.
So by next summer, I expect something like:
OUT: Sanchez, Eriksen, Vidal, Vecino, Kolarov, Ranocchia, Perisic
IN: Scamacca/Belotti, Frattesi, Vanhuesden, Bremer/Ginter, Kostic, Onana
Some other free transfers we could potentially target (though unlikely):
CB: Felipe, Romagnoli, Christensen, Denayer
Mid: Freuler, Kessie, Zakaria, Lingard, Tolisso, Isco, Corona
Str: Lacazette, Azmoun, Insigne