In my opinion, it is somewhat of a trade-off. Disney's Marvel films are consistent. You know what to expect, just about every time. In a way it's similar to their in-house animation studio or Pixar. With WB, Sony, and Fox, superhero films are still a gamble. Their best movies tend to be better than Marvel's best, but their overall bar and average quality level is lower.
That said, Marvel has already announced they're still doing Deadpool movies etc. So no reason to be too sour about it from the audience perspective. From the business side, big companies merging and consolidating is pretty scary, I agree.
THAT said, this IS the golden age of superhero films. I am a BIG FAN of superhero films. I have been in what can essentially be described as 'movie heaven' for about a decade and a half, and I realize that it will end some time, as all things must. This could conceivably be seen as a step toward that end. This is a strangely specific time to live in, where people still crave basic action movies with a side of humor, but expect complicated special effects, and have been conditioned to connect those things with capes and codenames. If it wasn't for superhero movies, I think we'd be in the same place, with people complaining about a different subset of action films ruining the market.
All I can say to those who are not fans is, your time too will come. For example; Throw, I'm sure some day bird movies will get really big.