I don't know about this.  There's an old saying that if money is good to have, more money is even better.  Even though porn stars can do product for onlyfans is safer and easier, that doesn't necessarily mean that they will give up escorting because, let's face it, they want to get as much money as they can.

This can easily be seen if you go to a strip club.  Sure, dancing naked on the stage can earn them a lot money if they are any good, and it's safe and easy.  But the girls will still do lap dances because, well, it's more money.  And they'll do "champagne rooms" and private rooms, and private parties because, well, they can earn more money.   And there are plenty of strippers who do blow jobs or more in the private rooms because, well, it's more money.  And there are quite a few that escort on the side because, well, it's even more money.  And so on.

When Chaturbate and Streamate, and Pornhub and similar sites came along, everyone said that it would be the end of dvds.  But, dvds are still being produced and sold.  A lot of people said that Chaturbate and Streammate and similar sites would mean that the girls wouldn't have to tour any more to strip clubs, yet they still do.  A lot of people said that those sites would mean that they wouldn't have to escort any more, yet they still do.  And more of them do now, then they did before those sites became so prevalent.

The girls that are trying to raise children on their own, will want as much money as they can get whether it's via onlyfans, chaturbate, streammate, touring in gentleman's clubs or escorting.  The girls that have drug and/or alcohol problems, will want as much money as they can get.  Etc.

It's all about the money.  I don't see onlyfans really putting a stop to the porn stars escorting.