Is there any indication all of the IronSource or other ad stuff will not be optional?
Not allowing developers to remove it from their games would certainly be a step too far (at this time anyway, who know what will they come up with in a couple of years).
The problem is that there is no way to trust that Unity will not alter the deal in an underhanded way in the future. I do not want my purchases beholden to their capricious whims. I sympathize with the devs, but sometimes it turns out that platform decisions made in the past are bad. It is what it is.
True, but there are certain things (e.g. including spyware in games not using their analytics and/or ads solution) some of their important customers would never tolerate. Then again they might just make no-"spyware" a "feature" only available in enterprise versions...
https://www.gamesindustry.biz/unity-ironsource-malware-came-...
https://www.pcgamer.com/unity-is-merging-with-a-company-who-...