No, we wouldn't.
We sold Coutinho for cheap because: 1) he wasn't really good here, 2) we needed to make an outgoing transaction, 3) the coach did not want to use him.
People seem to support this kind of transfers now, so I guess in retrospect they can find the Coutinho transfer a decent one... The same thing happened with Kondogbia, in reverse. He wanted to leave so we let him go, despite the coach wanting him to stay.
But Dybala would not have been sold. Just like Handanovic was never sold (there was interest from Barcelona, Liverpool, other PL teams and more recently from Napoli throughout his Inter career), just like we never considered to sell Icardi until last season and just like we have declined offers for Skriniar and Perisic in the past seasons.
If anything, it would have given us stability.
The only possible destination would have been Real Madrid and we'd be getting 60+ for sure in that case, especially since we'd be in the Champions League probably. And that would enable us to reach where we were in 2018-19 at least 2 seasons earlier. Pretty confident he'd ditch us if Real Madrid came calling and we weren't anywhere near winning the Scudetto.