Shopping portal Rakuten currently lets you convert points into cashback or American Express points (this was added in 2019 when Rakuten was called Ebates).But according to this page you can transfer points to Bilt.Interestingly that page lists both Bilt & American Express so looks like Bilt will be in addition to American Express rather than it replacing American Express.
Unfortunately it’s not possible to set up this new transfer. The terms do state the following:
Note that you can’t switch directly between Bilt and American Express Membership Rewards points.If you want to switch from Bilt to Membership Rewards points or vice versa, choose PayPal or Big Fat Check first, then select Bilt or Membership Rewards points.
But selecting big fat check and then changing doesn’t work.
We also don’t have any information on transfer rates.I’d be surprised if it wasn’t $1:100 points like the American Express option but no guarantees.
There are many reasons why people might prefer Bilt to American Express including Bilt transfer bonuses and differing transfer partners (e.g Hyatt & Alaska both 1:1).
Hat tip to awardtravel