Older age group IPs tend to rely more on public opinion, pop culture, trends etc.
Star wars and Marvel , for instance, are experiencing fatigue at the moment due to the declining quality of the film and streaming service output. Perhaps one of the many reasons the Galactic star cruiser hotel at DIsney world (alongside prices and running costs of course) was a failure. It's all relative though, they are still 'strong' brands, although the extent of their popularity does matter when it comes to massive investment.
That being said, I certainly don't see the Thomas or 'Thomas land' brand losing strength, let alone dying anytime soon. It's strength is the fact its kid focused, and nails the curiosity of young kids towards things like trains and railways. Which makes it a very stable, established and durable IP. and not as exposed to changing cultural trends in the same way as other IPs might be. It might seem intuitive that the series would be exclusively popular among young boys, but its also surprisingly popular among young girls too these days , too, according to what the TV figures on Thomas and friends say at least. Point being; it's a very strong, universally popular, and durable IP, despite the current AEG situation. And the series has over 500 episodes, so as the posters above say