For the most part there is nothing in the pipeline for Windows Phone 8.1 Update 1 and 2.
Update 2 rolled out to select phones, some people have done hackier methods to get it, but otherwise its not lineup-wide.
Otherwise most phones are on Update 1 and the most recent update for it was the random reboot patch from some time ago.
Microsoft is focusing on getting Windows 10 Mobile battle ready and 8.1's probably seen its last update, especially considering anything with 8.1 should be able to get 10 in one way or another.
Carriers can block updates potentially, but Update 1 and 2 are just about as up-to-date as can be at this time, so I would wait for 10's launch and the ensuing update mania.
So yea, 8.1's just sitting tight while 10's being bolted together.