I think we're going to see more events being organised and run by Merlin themselves, and fewer Attraction Source exclusives. The Merlin parks need to charge for these events, realistically, because they'll be over subscribed. There are far more people who would be interested in a behind the scenes / fan event at Alton Towers, Thorpe Park, Chessington World of Adventures and Legoland, than Paultons.
Paultons gave away 250 tickets for their Super Fans event, around 225 attended (according to the PR company rep I spoke with). Paultons can't compete with the Merlin parks with their gigantic marketing budgets, but they can engage with their community. Community events, management and building is what you do when you're a small fish, without much of a spend, and need to create an engaged conversation about you.
I overheard a vlogger saying to a PR rep that they "need to go to Merlin and get them to run an event like this". Merlin was in the back of everyone's head when they were at the event. "Merlin wouldn't do something like this", "Can you imagine being allowed to walk around Nemesis like this?", "Why don't Merlin do this?", "Wouldn't see this at a Merlin park". Merlin ARE the conversation, they don't need to wine and dine fans, or vloggers, they've got them queueing up for every scrap that's thrown to them. Additionally, for Merlin, it doesn't make sense to target and cater for that audience when they are running a PR event. The vlogging audience are already engaged, they need a wider audience. This is why you see soap stars, reality TV influencers, or local TV media, C listers etc at Merlin PR events and not vloggers.
A well known vlogger, who shall remain unnamed lest the legion of fans descend, often says that "Alton Towers wont work with vloggers". That's not true. In fact this particular vlogger did get an exclusive walkaround chat with Bianca fairly early on. Alton Towers don't need to work with vloggers.
In the early days, Apple's WWDC and Google's IO event used to be free for developers to attend. As these companies grew, and interest with it, they got to a point where they were able to and needed to charge for the event in order to control numbers and keep those who are truly engaged (and going to get something out of it) and not attending just because it seems fun / cool. This is where the Merlin parks are.