Holepunch Inc, the company, ceases to exist, or pulls the app from the stores.
For 99% of iOS users, that is effectively the end of their holepunch expereince. They cannot invite friends (who also not tech savvy) to install and join them for a chat, and if they lose their local copy of the app (get a new phone, etc.) that's the end of their own connection too.
Yes 1% might compile from code and install via their own personal testflight or whatever, but when talking about general adoption of decentralised tools there is no sense talking bout that 1%. Most people don't even know what the word "key" means, let's not forget.