There's too wide gap between OLAP and OLTP DBs, but definitely hybrids will appear. Vanilla pg is great but it's far away from analytical workloads. I use Vertica at work, it's a OLAP DB, but it handles hundreds of concurrent users in a light transactional workload without any issues (even though its locking isn't as granular as the one in postgresql). I would say that there's a spectrum between the two types of DBs and there's a market for all.