Retirement.
In all seriousness, it depends. And not just on specialty (though if you're doing full time, aiming for CCT, then specialty plays more of a part).
You could finish FY2 and perma-locum part time, for example. If you don't mind not being linked to one location and not progressing to reg/consultant, then in London, you could work 20 hours a week in A&E for more than the average full time wage in London (and have an extra 17 hours a week to play with).
Equally, you could go through GP training and 5-6 years after completing your degree be doing the same on 8 hours a week, i.e. one shift, often able to be worked from home. Equally, you could meet in the middle and get to consultant level in a specialty and do the same. However I think most people tend to stick with the NHS directly