Here's the thing: almost all of the facts presented above are speculation. They're just guesses, as opposed to actual set dates and facts.
You also have to keep in mind that the show's primary focus is merchandising, and to make Hasbro money. It's no surprise that it has been a strong seller for Hasbro, but markets and economies fluctuate constantly. There is no telling what the market for MLP products will be like in a year, in five years... on however long.
You need to realize that you're getting stressed out over ideas and details that have yet to be set in stone, let alone even organized and presented better. For now, the show's going strong, the merchandise is selling, and there still tons of fans everywhere. Unless there's a serious, and I mean serious, change in direction, quality, or likewise, it's probably going to be around for a while.