Valentine2
Personally, I believe Brexit is still a poison chalice. If May does push ahead and the economy suffers (even - if you believe some Leavers - just for the short-term), she'll likely be out by the time the next elections are up.
Also, the demographics are likely to change over the next few years. People who were too young to vote on the EU referendum will be voting age by then. In contrast, since older people were more likely to vote for Brexit, I'm afraid to say some of them will no longer be with us by 2020.
The Brexit vote will make many EU citizens become UK citizens over the next couple of years, too. Most haven't done this previously, simply because they didn't need to. But I believe that even if EU citizens were granted indefinite leave to remain, the Brexit vote will have shown them that having no vote at all in the UK isn't great, simply because a large proportion of the electorate seemingly had no bad feelings about ruining their lives. Many will choose to get British citizenship just because of that. There are 3 million EU citizens in the UK. If they had a say, it would change the direction of the country (and I do believe that naturalised citizens are often more politically active and have less voting apathy than those who were citizens since birth).
If Brexit was seen as a protest vote against Westminster and London, the next general election may be used by Remainers (and the millions of new voters listed above) as a protest vote against the government that actually chooses to make Brexit happen.
It's a difficult balancing act. The Tories can choose to follow the results of the EU referendum, but in doing so, they will likely have to relinquish power. Looking at the last few decades of British politics, political parties are more likely to ignore voters than relinquish power.