You might find this thread useful:
http://forums.audioholics.com/forums/showthread.php?t=67521
Right now, there are great deals available on a Yamaha RX-V1900 and a Marantz SR7002. You can get either one for about $600 delivered (from places like Amazon and others), they are both solid and good, and both retail for about $1400. The reason for them being so inexpensive is that they are discontinued, and, I believe, they are not capable of 3D passthrough. With reasonably high end units, a lack of the latest features tends to cause the price to drop dramatically, and so you can get great deals on them in cases like this.
If you want 3D passthrough, you will pay more (if you want equal quality to the above models), as that is only on very new models. But if you don't care about that, then you can get a great receiver for a great price.
I recommend that you visit the manufacturers' web sites and make sure that whatever you buy has the features you want.
As for how long they will last, if you don't care about 3D, they both seem about as ready for the future as anything, and I doubt you would need to replace either in the next 5 years. Of course, manufacturers like to add new things (like 3D), to get people to replace their old gear that works perfectly with something new.
If you get really difficult to drive speakers in the future, you will most likely end up with a separate power amp, and to use such an amplifier, you need preamp outputs, which pretty much everything at this price point has (though check and make sure on the one you plan to buy before you buy). But both of the above should handle most speakers without difficulty.
If you do care about 3D, the above models can still be used if you get a 3D BD player with two HDMI outputs, so that you hook up one to the receiver and one to the TV, but it is generally less convenient to do things that way. But getting a $1400 receiver for $600 is such that one might want to deal with a little inconvenience if necessary, but only you can decide what matters to you.