Cockroach DB recently addressed hotspots on sequence/timestamp workloads with: https://www.cockroachlabs.com/blog/hash-sharded-indexes-unlo...

Does what it says on the tin for the primary key.

That said, hotspots are 100% the reason why Cockroach encourages UUID primary keys. The disadvantage to UUID is you want sequential data, you then need a secondary index which you'll have to bucket anyway.