35c3 has been confirmed again in Leipzig, Germany:
(German, sorry most news articles are): https://www.heise.de/newsticker/meldung/35C3-CCC-Hackerkongress-findet-auch-2018-in-Leipzig-statt-4153769.html
15.000 people have attended last year and 17000 are expected this year. The CCC is a bit slow this year with news but they confirmed it via twitter: https://twitter.com/chaosupdates/status/1036009379516932096
Tickets are open in November / December, although it can be tricky to get one. If you are interested please mention it so here so we can try to have some spare tickets maybe. They start around 120 EUR for the whole 4 day congress.
I have been at 33c3 (Hamburg) and 34c3 (Leipzig) and it’s a not-to-miss event. As the dates are around Christmas and New Year’s eve (27-30th Dec) you should expect to plan ahead. It’s suggested to fly out to Berlin and take a train from there to Leipzig (1-2h, 40-80 EUR return)