I would take a serious look at some of the newer PRC calibers. They are fantastic from a ballistics perspective and ammunition is quite easily obtainable. I also think these are calibers that are going to be around for quite some time, opposed to other "fad" calibers that are quick do die off after a few years. 6.5PRC, 7MM PRC and 300PRC all good choices.
If you currently shoot a 7mm rem mag and want something a little bit lighter, the 6.5PRC would be a good bet. If you take a look at ballistic tables you will see the 7 rem mag has more energy at the muzzle than a 6.5prc will, but that the 6.5 will hold its energy a lot better and take over the 7mm energy wise at a certain distance.