I think this whole argument is pointless. People will not be skipping HK and jumping to ID unless they are going to be carried. Guilds will continue to do HK for the gear while doing ID. What we will see is guilds not going the complete 11/11 before 'moving on'. They'll go in and do lower levels and even some of the top while working on the hopefully easier 'beginning' ID bosses. And with the gear upgrades those last 9+/11 HK will be much more doable.
It's not like the two instances are mutually exclusive. All this will depend on Trion, will the new ID gear/tokens be better then hex? Will the upgrade path be like GMoA, ID Marks, HK Hex, ID Hex? Will the time/effort be rewarded with more GMoA or less ID Marks to make it worthwhile. It'll depend on how stingy ID tokens will be.