Whilst I think everyone should vote that's not a prescriptive opinion. Democracy is about choice and if you are compelling people to vote you are removing that choice.
I also don't necessarily buy the assertion that everyone who doesn't vote is too disillusioned by the lack of choice, it's because they don't care.
When the result is uncertain people turn out, in 1992 the turnout was 77% which is quite possibly a post war record. I think the turnout will be reasonably high this time for the same reason.