Are Shimano 10 speeds going away?
They're trying to sell you stuff. More expensive stuff (have you looked at 11 speed consumable (chain+cassette) prices vs 10 speed?).  I would not bother upgrading. 

As groups go to higher and higher speeds, the older stuff gets pushed down to lower component levels. So today's 11 speed 105 group will be next year's (or likely a few years later) Tiagra group (with some minor modifications). They're generally completely compatible with the previous higher end stuff. The price might change a little bit higher or little bit lower, but it won't be bank breaking (in fact, I'd guess it will go lower, at least for a few years). And let me remind you that we still have an 8 speed road group, despite 8 speed being 20+ years past introduction (heck, 9 speed is nearly 20 years old and we still have a ton of parts on the market from shifters,cassettes and derailleurs; 10 speed is only a mere 12-ish years old; 7 speed stuff is still in abundance, though finding quality components has started the incentive to move 8 speed). 

So, you should be good for quite a while sticking with the 10 speed stuff. Unless you need the shiniest fanciest stuff for some reason. Plus, if you do decide to go 11 speed for some reason later, it will be cheaper than doing it now.