Ulster's propping situation is unfortunate. They're going from an area of serious strength to an area of uncertainty. With regards loosehead they should be given some leeway. As has been mentioned, with Kilcoyne, McGrath and Healy all playing regularly (the latter due should be able to get enough time splitting the Leinster 1 shirt) Ireland are reasonably well covered, so a NIQ shouldn't be out of the question. In any case, Callum Black has really grown on me as a LH option.
At tighthead it could be a different scenario, depending on how the IRFU judge things. On one hand Martin Moore is developing at a rate of knots, while Stephen Archer is improving and Nathan White will soon be IQ, which would leave us in a good position. On the other hand, none of them have shown themselves to be capable of propping up an international quality scrum, something Deccie Fitz has in the past. The IRFU may be pretty keen on him being Ulster's starter. This presents a problem in that not only is he a huge step down in terms of quality, his fitness is anything but assured. Ulster will struggle to bring in a top replacement who'd be content with sitting on the bench for the HC games, but they do need a good operator there. Hmmm.