Making the switch to wireless ac is worthwhile and the best way to go about it is just as you are doing by updating one device at a time as the opportunity presents itself. Since wireless ac is compatible with all previous forms of wifi, interconnectivity will not be a problem. There is one issue with using the Intel 7260 card in your specific computer, though. I have read somewhere that the 7260 will only work on Intel Haswell-based computers. I believe it even mentions that on the Intel web site.