Everyone is still stuck on 28nm for budget tablets socs. Thus the cpus are the same more or less than what we had 2 years ago. Sure for the OEMs their cost for other parts have gone down but they kept that as profit and we have not see a drop in prices for any android quality tablet that are in the $<300 or below range.
Windows is pretty much in the same thing with tablets, but instead of the last 2 years make that the last 15 or so months since baytrail came out. Sure there are now 1gb tablets with windows, but the 2gb models are still about the same price.
Now for the higher ends prices like $300 plus for android, and $400 plus for windows we have much better high end, but they still cost about the same as the old high end. It is only on those higher price points will you see OEMs go to new SOCs such as the qualcomm 810, intel atom cherrytrail x7, intel core m, etc.
Until an OEM is willing to price a medium/high end device in the price range currently occupied by the "budget tablets" we are not going to see specs improve in this price front. We will see lower tablet prices, but those tablets will be something you do not want for you get what you pay for.