PFL has gotten with RIZIN about keeping the partnership they had with Bellator, but my first thought there was that PFL is trying to swing RIZIN into sending a RIZIN GP winner to their own tourney, that way they have a legit representative from Japan for their WSOF, and don't have to foot the bill in getting that fighter to where he needs to go, RIZIN gets to do that. Right now, we have PFL, PFL Europe, Bellator, PFL Challengers, with PFL Africa and PFL MENA on the horizon, and presumably PFL Australia/Oceana and PFL Brazil, down the road. Partnering with RIZIN allows them to not have to go through the trouble of setting up shop in Japan, RIZIN can just do what they do and ultimately a chosen fighter will be sent over to fight in PFL, and add to that true world flavor PFL is seeking.
Idk that it really plays out that way, was just my first thought. But I think that orgs tend to not do these things bc the partnership is really just using another org to springboard your own, and Japan always tends to take the W in those situations. I'm interested in seeing how that plays out, bc the Bellator partnership was a handshake agreement between two legitimate friends, that was certainly set up to benefit both orgs. Idk that Sakakibara will view it that way, dealing with PFL. PFL might get want they want, and RIZIN might be ok with giving them that, but I have a feeling that what Sakakibara will want, he will get, and PFL won't be as ok with that part.
And I think that sums up why we don't see it more, the co-promotions and fighter trades we got between Strikeforce and PRIDE/DREAM and later RIZIN/Bellator were on the back of a great friendship between promoters, and aside from that example, these guys running the orgs are businessmen, not friends, who don't actually care about helping anyone, only themselves. PFL probably gonna find out the hard way.