Indubitably. But transferability—the lifeblood of UR—is a thorn in United's side, given Chase's CSR/CSP cards competing—and winning!—against United's. This begs the question, Would United suffer if it found another bank to issue its credit cards? Methinks not.
Yes, but would Chase suffer if it lost UA, one of it's most valuable transfer partners, for those undeniably successful UR earning cards? Methinks so. I think Chase has a huge incentive not to cut themselves off at the knees here. They developed a terrific and valuable program with resounding success. But they need those partners. If UA left, and left the UR program, than Southwest would be the next most valuable airline partner (IMO), and that would leave most of the Eastern, Midwest and Southern part of the country finding those "valuable" Ultimate Reward points not quite so valuable.