Fine by me. I think running multiple overlapping loyalty programs for the most part adds clutter and reduces engagement of "normal" people (i.e., not enthusiasts on FT).

The tricky thing is going to be what you'll be doing with RA/Kimpton Inner Circle. If you don't give them a new top tier in IHG One Rewards, they might get the feeling they are being demoted als Diamond is less special than Diamand RA. If, instead, you do put in a new tier above Diamond, you satisfy your RA/Inner Circle clients but might dis-engage Diamonds for whom the new top tier is out of reach.

Two possible compromises. (i) Make the new top tier not that hard (at least initially). That way, you disappoint only a smaller share of non-RA Diamonds (the less valuable ones). But you might actually get more business from those non-RA Diamonds who can muster up the additional spend required by the new top tier of IHG One Rewards. (ii) Update/further develop the milestone programme so valuable, former RA/Inner Circle customers get recognition through that. That's a bit tricky, though, as currently milestones are solely based on night count.