We would be incredibly foolish to allow him to leave. I understand the "you're free to leave whenever" mentality but it has to have limits. There's nobody on the planet even close to Ederson, our entire approach will have to change if he leaves and we instantly drop from being untouchable if a team wants to high press against us to it being a viable approach. People have become too used to edersons brilliance, once he's not in net every week many who are downplaying his importance will quickly realise there's nobody more vital than him.
I rate Ortega highly, very highly but he doesn't come close to being a replacement, we will have been significantly weakened if this happens and that's not ideal when you've got Pep for a limited time. Ederson is still young for a keeper, if he wants to go earn stupid amounts of money for a few years he will have the opportunity further down the line in the back end of his 30's, him going to Saudi now would be like a 23 year old outfield player making the move.