Ghiotto to STR sounds to me like Italian website being wishful thinking about Italian driver. Although Ghiotto is a pretty good driver.
Would be more in character for them to just promote immediately Vips next year straight from F3.
Alternatively, they could relegate Gasly swapping him with Kvyat; or not even need a Toro Rosso driver change at all if they sack Gasly completely and hire a Max team-mate from somewhere else in the grid.
Point with extern, it would be for multiple years you would assume. And by that, what signal gives it towards the "junior" drivers? Albon instantly knows/thinks, "also with 2 or 3 good STR seasons, i likely won't get promoted, are there other good seats available?"
Gasly only has very few races left to impress Marko/Horner, but i suspect it's already to late. He will end season, but what is there to gain for Red Bull to place him in STR again? Is it likely he will recover, or just like Kvyat needs off (f1) track season before, or if ever coming back towards F1? And even if he recovers in STR, how likely is it he when needed then will perform in mean team? For Gasly you would hope he at least kept a seat, but with at least not under performing STR drivers and need new generation securing by having the valuable selling point "fast intern promotion possible" i can see Gasly dropped all together now and promoting Kvyat and rookie besides Albon in STR. While Albon isn't underperforming in comparison Kvyat, i think Red Bull is by that also rather what more protected of him and Kvyat has the easy to sell reasoning "proven podium driver" to justify his promotion above Albon.