I wouldn't be surprised if Chipmixer disappears within the next year or two. The average time for a mixer services seems to be around 3 years. 5 the strongest ones, as low as 1 for the weaker ones. We just had Bestmixer taken out by the cops recently... hopefully im wrong but that seems to be the trend. Chipmixer will probably go away in similar fashion than Bitmixer did. Probably even if the site isn't annihilated by the cops, the developers may just become increasingly paranoid after X year and start afresh.
In a way, not that different from exchangers.. Livecoin may go cryptopia eventually. Again, I hope im wrong, but let's not be naive here. Most crypto related services are short lived, except those that have heavily regulated.
Decentralize all the mixers! Make them un-cop-able!
Not possible in the classic sense of a server involved. Maybe with lightning network, but then again, there's people that will not trust anything but on-chain transactions.
Perhaps look into CoinJoin with wasabi's blinded bearer signatures as an improvement for the classic "dude hosting a website for tumbling coins" approach. There was recently a 100 people CoinJoin transaction which was successful.
Note that a server is involved in wasabi but the stuff that's logged wouldn't allow an attacker to connect ins and outs.