No. The thing is that there is not much to improve upon. The AC standard for wireless is relatively new still, and the current models have Beam Forming.
Now back in the Wireless N days there were 5 generations which all looked the same which brought various features like more powerful antennas, Gigabit Ethernet, etc.
I don't see the Time Capsule as getting an update anytime soon as AC wireless is just being adopted now.
Same suggestion. I am now still using the last generation TC. Not even think about to upgrade it. The current TC should be pretty good for the next few years. Unless you don't like the current design, and looking for a new design from Apple.
I just got a Time Capsule a few weeks ago and am really happy. The AC wifi is fast - I get about 30MB/s read and 28 MB/s write copying files from my MBA to the internal disk. I put my 400GB iTunes Library on the Time Capsule disk and can access it wirelessly on my MBA just like it was on the internal SSD (I use thunderbolt drives for Time Machine).
I'd get one now over waiting. There's nothing to improve and Apple doesn't update their routers very often so their's not much of a risk to getting one and then seeing an update come through
If the capacity needs are OK at 2TB/3TB I'd agree with the other replies, go ahead & buy now. If there are any updates I'd expect maybe a capacity boost so if you'd be tight at 3TB you might wait a bit.
I'd get one now over waiting. There's nothing to improve and Apple doesn't update their routers very often so their's not much of a risk to getting one and then seeing an update come through