The topic of UB is continuing to create controversy as the number of non-Magic IP products explodes. The Professor put out a recent video on the topic predicting a future Universes Within product to make up for all the unique UB cards being added to the mix, but looks like MaRo has quickly shut that idea down.
What are players who don't like UB supposed to do when there are no Magic versions of those cards? This is now just reality.
I think the most worrying thing mentioned in the video is how many sets are planned to be released for the Marvel universe. We're looking at probably 2-3 years of continual Marvel-related releases, and I think the overall effect that will have is that the UB sets are really the first-class citizens and the regular in-universe sets are actually secondary. I think people will start to associate the game entirely to these UB sets given how much press and coverage and marketing they get. I think enfranchised players will start to look at other games in increasing numbers.
It's impossible to predict the effect this will have, and the effects could very a lot depending on the target market -- casual players may increase but competitive players may decrease for instance. However, one thing I believe for certain is that the way people think about Magic is already fundamentally different, and that UB sets will only continue to increase in total share of printed cards will further change the way people think about the game. At some point, you're not playing Magic anymore, and the players aren't really the same type of people/players as they once were.