Clearly a combination of the TV debates and the hard-to-predict outcome is adding to public interest - all of which point to a high turnout. On top of this we have the news of a big late rush of applications to get on the electoral register.
That’s plausible. But think about this:
A late rush to get on the electoral register will mostly consist of people not usually interested in voting. If the various novelty factors in this campaign have worn out come polling day, these are the people most likely to stay at home. So a rise in registration could be setting us up for a fall in turnout.
(Although, of course, I mean turnout relative to the number of people registered, not the absolute number of people voting.)