Adobe's history of acquisitions is probably a good indicator to figure out where the Magneto stuff is going. Usually when Adobe buys a product they do alright with maintaining it. They pretty have never really knocked it out of the park, the most they've done is kind of middling amount of success where they just don't mess anything up. For example, neither Flash nor ColdFusion really took off after Adobe acquired them, but each has basically been slowly dying due to extended periods of "doing alright I guess." Each integrated with the rest of their other offerings but in a way that seemed mostly to offset the change in direction being acquired introduces. I kind of see Magneto following the same course. It'll kind of continue just kind of being "a thing" for the foreseeable future.

Not to mention, in general when companies try to assemble a portfolio through mass acquisitions it rarely seems to ever amount to anything other than "middling success." If the parent company had the discipline, talent, and internal processes capable of producing quality results, they likely would have just developed something on their own. Meaning once they actually get the thing they bought the most they can hope for basically is "product integration went alright."

TBH Drupal will likely benefit from the sale. Magneto was/is the CMS that's just behind Drupal in terms of open source CMS market share. Being purchased by Adobe means that Drupal doesn't have to be wary of Magneto biting at its heels anymore and can worry about growing its market share at the expense of those with more of it.