Well, April to July=12 weeks and I stated it as what amounts to several weeks. At least a short enough time for dealers to be aware that a 2016 was imminent; especially if they told a customer to expect a late July delivery and that the 2016s would be way off-like the winter. And I suspect that when you bought your 2010 in July you were aware that the 2011s were coming in August? At that time you had the informed choice of getting a 2010 or 2011.
My point is, the argument could be made of should I take delivery of a 2015 when it has been indicated by some here on the forum that if I now were to wait a few additional weeks I could get a 2016 with potentially additional features? The UK 2016 specs indicate as available: 17-speaker Meridian audio, InControl Remote Premium with lock/unlock/heat/cool, hands-free powered tailgate. As a related example, the 2016 Evoque has had a refreshed interior and additional features added with supposedly comparable pricing to its 2015 predecessor.
I'm not interested in arguing about weeks, so I will submit that 12 weeks is several weeks. And IMHO, still long enough for a model run for a whole year. That all said, They have to change at some point and later in the year seems more logical; say October/November. I totally agree it sucks to get a 2015 when the 2016s are just several weeks away.
Actually, back in 2010 there wasn't a lot of information on when the model year would change and what new options would appear. Now, the web is full of leaked info, some valid and some not. So no, when I bought mine in July 2010 I had no idea the change would be made so early for the 2011 model year. I also suspect that there may be variances from model line to model line: RR, RR Sport, Evoque, LR4...
I'm going to speculate we don't see the 17 speaker Meridian or HUD display any time soon in the US spec DS. I would love to have both along with any other goodies I can get my hands on ( read the new 2.0l oil burner slated for 2016) . They obviously add those in other markets, Canada, Europe and who knows where else. I suspect that this is a price point move for JLR and they have purposely de-contented the DS here to keep prices low. Add another $2500 for Meridian, $900 for HUD and what ever else and you are getting close to $60k for a fully loaded entry level vehicle.
My suggestion is to just be happy that you have a very nice vehicle to drive around in. Enjoy it and don't sweat it too much that the new model year is coming out. I suppose you could always tell the dealer you want a 2016 instead of the 2015, just have to wait a little longer to get it.