For people with type 2 it is still possible. While some people seem to come out of surgery with diabetes in remission (my case ) plenty of people only go into remission as they lose their excess weight. I have seen posts of people that weren't helped at all although they seem to be a pretty small group.
It seems to depend more on why you developed diabetes and in some sense how long you've had it.
It's also important to note that having your diabetes in remission doesn't fix any problems that might have developed due to your diabetes pre-op. For instance, I have pretty bad neuropathy in both my feet. Just not much feeling - no pain but it leaves me still open to damaging my feet before I realize I am doing something wrong.