I'm torn on the whole app thing.
Is it possible to do it in a way that makes the user experience not be bad at all and keep crowds relatively dispersed? Sure. IoT/Internet of Things tech is so far advanced now they can do it...provided they are going to invest millions of dollars into it and that they already started months ago. There's not a ready made, plug and play solution. But using advance analytics/AI to sense the data and flow of people in the park, if everybody group has a reliable, continuous connection to the app is certainly doable.
There are the obvious potential issues of connectivity, people closing out the app to save battery life, battery life in general with an "always on" location-based app, technology hiccups grounding operations to a hault, people confused by the process/not wanting to follow it arguing with operations people (people can't even even figure out the express vs regular lines and clog up the works, this is exponentially more complex), inebriated people trying to follow the app, etc.
But regardless of all that, the one glaring issue I see is the virtual queues. If they limit capacity to half, just spitballing here and making up numbers, and there are no lines...that means about 90% of ALL people in the park will be roaming the streets at any given time. Think of the busiest night you've ever gone, when a couple houses had 3 hour wait times and all other houses were close to an hour. Now cut those lines in half, so 30-90min each line. Those lines don't exist...so all those people would be ADDED to the streets. That's just insane. Just think how crowded it is walking around when you're not passing/mingling with all the people in lines and shows. I would think that at least 50% of crowds each night (again, pulling these numbers out of my keister) are actively in lines or in show venues at any given time. I'd argue it's probably closer to 75-80%. If you put them all back in the streets, I don't see how it could possibly work. Unless you do a konga line through the park, everybody slowly makes their way to house A, then to house B, then to house C, with people starting their night at different points in the cycle, it's just going to be a mass of people walking by each other, or worse still, congregating in lines for beverages and not following the rules. Again, if lines are gone (well, reduced by about 90% say since you obviously won't just walk directly into the house at your assigned time) those people will be on the streets. I just don't see how it could possibly work out.
I would think the max attendance, for the busy days, that this could possibly work and keep people socially distances would be 25% capacity at the absolute max and that might not even be feasible. I'm thinking something like not only having the app do your visit, but you getting a 2-3 hour time allotment in the park per visit might be required. Like some nights the app might tell you to show up at 6pm, other nights you might not be "allowed" to show up until 11pm or even midnight. That could really help break up the crowds, but haven't heard anything like that (yet). But think of the 9-10pm peak times, and cut that in half, that just doesn't work. Cut it by 75% and factor in no lines and it's still nearly impossible to believe.
Not trying to scare people or start a forum war, just my nerd brain thinking out loud and not being able to see how the currently rumored plan could possibly work with the rumored numbers. I think the technology surely exists to impliment a successful plan, but not at the scale with the physical limitations of the park (particularly the central lagoon restricting several places to only one route from point to point).
EDIT - I should add that I don't think that there will be NEARLY as many people going this year. Locals, sure, but the huge UK population needing to plan airfare and stuff and worry about travel restrictions in the time when flu season usually starts...I think attendance will be cut at least in half just based on people wanting to avoid crowds and logical issues for travelling and wallets tightened to do economic and employment issues so it's not all doom and gloom for those willing and able to go as I think the crowd will be greatly reduced organically without Uni having to restrict it.