I don't think the government will ever come out and say 'no more socialising for ever'. I think that would, as you say, lead to a massive backlash. However, I think instead we will see a repeated extension of the powers, which will have the same effect as a permanent ban. Over time, I think some proportion of the population will ignore the rules. But the majority have been so terrified into submission for the past year or so, that the number breaking the rules will likely not be a majority for a very long time, if ever.
Sadly, I think that to expect that society will go back to pre-March 2020 normal (i.e. seeing friends and family, making new friendships/relationships, doing the leisure activities we used to do, going on holiday, not living in a constant state of fear), is unrealistic. I say this because we are in the midst of the most extensive period of social engineering in human history, with the end goal being something which we cannot ever do, to avoid death by a viral disease at all costs. We massively underestimate the damage that the past year has done if we think that we will ever go back to living how we did before March 2020.
I don't think there is any gain for them. But they have made a permanent, damaging, change to society which I don't think they will be able to undo. To repeal all these laws would be to admit that they were either a failure, or unnecessary, next time there is an outbreak of a respiratory virus (or if Covid makes a comeback).