As someone who's been trying to get into the PayPal platform program (PPCP) for nearly two years now, I almost had a stroke reading this headline thinking I could have all along just committed to Stripe and received the same functionality in my product.
Beyond the fact that this is EU only, it does seem like ON_BEHALF_OF will probably never be supported considering PayPal would be directly feeding their competitor with the same functionality that their own platform offers.
That being said... onboarding into PPCP feels like getting selected for the lottery compared to just how easy it is to get running with Stripe's platform. If Stripe ever does support PayPal payments on behalf of I'd be switching over in a heartbeat.