Swapping Pogba for Verratti+money would be the most logical thing to do if Pogba wants to leave. Replacing Pirlo will be extremely hard and Verratti is the closest thing to Pirlo we could possibly get.
We were doing fine before signing Pogba while we were horrible before having Pirlo. The problem would be to have Pirlo and Verrati play together since we are going to extend Pirlo's contract, which would be difficult. However, I'd still do it.
I don't buy all the crap about Pogba being all that better than Verratti. They're different players but I find quality playmakers like Verratti harder to find.
Don't get me wrong, I love Pogba, but it is far from the end of the world if he goes, especially if we get Verratti and some money in return.