As far as I know, this year would have been at Hamburg again where the number of participants is capped to ~12k. So it would have been slightly smaller than in Leipzig.
Which is a pity, it will be notoriously hard to get tickets.
My dream would be ICC Berlin with it's spectacular architecture, it's also huge.
The only drawback is that it's currently standing empty with no plans for it's future.
Trouble with ICC (besides it being closed for years now) is, that it's quite small on the inside. You could say it's a landed space ship that's smaller on the inside. You could of course also use some halls (14 & 15, because of the bridge for example) of the fairgrounds next door, but I guess all of that had already been discussed when they moved to Hamburg for the first time and when they moved to Leipzig from Hamburg.
I don't think the spreading would be reduced with fewer people if the venue is at capacity, presuming a similar people per m² regardless of the venue.
