There really is no cause to worry like at all that the developers would make stuff that be classed as 'hard raid content' mandatory for story.

CT has heavy ties to ShB as does Omega and Alexander the latter two are not becoming mandatory therefore it is safe to assume the stuff to do with them is not needed and if they ain't needed leading out of ShB they never will need to be.

Mhach series won't be mandatory until long after they reintroduce the redbills in msq so until you see Cait Sith in msq you ain't need to even think about them.

Ivalice and quite frankly it seems the whole of Western Othard looks to be all side content relagated to instances so until they have you meet resistence members in msq I doubt these will be mandatory anytime soon.

Do bear in mind it was advised prior to 5.0 to do CT raid series but are becoming mandatory in 5.3 so they gave you nearly a year to get these raids done until you hear we advise you to do x content you don't have to worry about it and when they do advise you safe to say you have a full year to get it done, would not be hard to do that.

Very much feels people making a mountain out of a molehill on this one.