I could see things that are seen as "staples" by many being present in multiple packs, if they support multiple power systems. Case in point: MFR. It supports multiple systems, even adds a little generation of its own, and is pretty much the go-to mod for farm automation...at least, for me. Mekanism is another because it can be run directly off RF, I know if nothing else, the energy cubes can directly input and output in RF using EnderIO conduits. Mek also adds superior ore processing capabilities, with significant investment of course, and has overclockers just like IC2 and even has what amounts to efficiency upgrades. AE is likely another given, even though I personally have some rather strong misgivings about what I've seen in regards to its upcoming overhaul. RotaryCraft is another mod that has conversion support for multiple power systems. Is it a bit graphically intensive? Sure, perhaps even moreso than most other mods; that doesn't mean it isn't an awesome mod.
However, I'm sure Jaded and Co will make good packs, they always do; from the original FTB Beta A pack back in the 1.4 days all the way to today. With 1.7 and what it adds, it'll mean that making sweet packs will be even simpler, and our configs may not be as crowded with ID definitions and such. With all that config code gone, mayhaps we'll see some new options in our mods in the future.