If it really is in their plans now to explore different character interactions then Raritwi is bound to happen. It may come up sooner or later as an opportunity to at least do something original, as it is mostly uncharted territory as of now.
Then again Twishy was also pretty unexplored and it got the lukewarm Hooffields and McColts episode, so finding the right plot to capitalize on both characters' strengths is important.
The best thing about it is that it can bring both characters in positive light. I even started to warm up to Dash after all these paired episodes lately.>>29805136
Rarity balances out anyone she's paired with without losing the lead. The only mostly one-sided interaction I think is Raripie. I would really like to see Pinkie playing more on Rarity's field but I guess Pinkie's unending enthusiasm is just that infectious.