Hasn't SMS proved to be a little bit of a one-season-wonder, Mike? Only caught them once or twice this season & he was quiet, plus there's been zero word/hype about him until the recent Juve links.
Think he may have been a dodged bullet, but maybe I'm being harsh. 100M does sound a bit silly given he hasn't really done anything to maintain that value. Think I'd rather look at the likes of Maddison (Good lad, lots of quality, PL proven, big upside & cheaper), Eriksen (arguably best AM/interior in the league), and Bruno Fernandes (cheaper, workaholic and can't argue with his obscene output, albeit Liga NOS) as replacements, whilst signing someone at base (Partey!!!! €50M RC!!!) & Ndombele at 2nd CM.
He's not been as good. But he's still great
It's more a general point though. Any Pogba type replacement is going to be 70m.
And if we do it right as you mention, we could get two players for him. And still not touch our initial budget. That's why the club should remain strong, as well as the status of not being held to ransom by players.