According to German newspaper "WELT" the investment group "emodrom Group" purchased 74,99% of the Hockenheimring from the local municipality. It now wants to invest 250 million Euros (~275 million US Dollars) additionally to the 40 million it has already spent to make the venue fit for the future. Planned are the construction of a 30.000 to 50.000 m² big motorworld, an expansion of the "Porsche Experience Center" and a new hotel.
When asked about a possible return to the F1 calendar, Hockenheim managing director Jorn Teske, explained that the Hockenheimring had always had contact with F1 but that they are planning to make a "slow and serious" return. Tim Brauer, head of the emodrom Group added "We need to ensure that we won't run into a deficit." Brauer further explained that in other countries the nation or federal state is happy to sponsor F1, something that hasn't yet been the case for the Hockenheimring. "We are thinking in terms of 20 to 25 years - and not short-term" Brauer concluded.
In case of an F1 return the circuit would have to meet F1's new criteria including 4000 - 5000 VIP seats instead of the 2000 that are already in place, fan zones, places for concerts, camping spots, etc. An expanded or entirely new pit lane building is also in the talks.
Source [German]: https://www.welt.de/sport/formel1/article253015118/Formel-1-Millionen-Investment-Comeback-des-Hockenheimrings.html
Edit:
I wrote "Tim Brauer, head of the emodrom Group, explained that the Hockenheimring had always had contact [...]." but it was in fact Jorn Teske who said that so I corrected it.
