It doesn't have to go that far at all, China and the rest of pacific rim slowing down faster than people expect will easily hurt that pair, there a variety of other scenarios that could occur as well. Directional risk is still there; the leverage you use for those triplep-digit APR's will hurt you just as bad in this department.
Just because time is nominally on your side does not mean the risk you take is necessarily worth the reward -- you still need to time your entries into these pairs to come out ahead. Selling naked options is also generally profitable based on time decay alone but that's by no means the complete picture.
As for differentials going away, my point is that traders will anticipate that reality way before the nominal rates begin closing those gaps; in that case the interest gained won't make up for the directional losses by the time differentials narrow significantly. Again, it all depends upon to what extent markets have already discounted that possibility, and how many players still remain caught looking the other way.
Just because time is nominally on your side does not mean the risk you take is necessarily worth the reward -- you still need to time your entries into these pairs to come out ahead. Selling naked options is also generally profitable based on time decay alone but that's by no means the complete picture.
As for differentials going away, my point is that traders will anticipate that reality way before the nominal rates begin closing those gaps; in that case the interest gained won't make up for the directional losses by the time differentials narrow significantly. Again, it all depends upon to what extent markets have already discounted that possibility, and how many players still remain caught looking the other way.