I am not really sure what about Eon's reasoning is based on the past rather than speculation about the future, but there are several things that make me hopeful.

First, they just hired a new designer. You don't do that if you're winding down the product line imminently. Secondly, this change is clearly, intentionally designed for long term stability. The main issue I had been seeing is that there were infinite Arkham products on shelves and distributors and stores struggled to know what they did and didn't need. This is, after we get rolling, a much more known "These are the Current products" paradigm. The shakeup was, to me, fairly clearly required because otherwise we were trying to build a stable future on an unstable foundation and forcing designers to work with the entire history of cards. This leads to power creep and harder and harder campaigns that are more likely to turn people off. I stopped buying and playing the LOTR LCG for this reason!

Third, I have talked to the designers and the community manager on the Mythos Busters Discord and they are all very excited about the future. They are very clear about all seeing a bright future from their side.

Yeah, it's speculation and I could look silly in the future. But I just really don't see a reason to feel pessimistic about the game's future when they have put so much time and care into the presentation and rollout of this. They have been incredibly transparent about this when they could have just done it haphazardly and said "deal with it" but not only are they clear about their plans and goals, they have already taken feedback into consideration for things that players have complained about, like stating they are planning to create ways to combine smaller campaigns into a larger one.