All books are a priority, but there are also the limits of time and space. If Matt could have written everything and gotten them all to come out when they were supposed to, then he would have. But when that’s no longer possible, then you need to make the best choice you can. As for assurances, there are never any assurances, anybody could leave any book at any time–that’s life, it’s uncertain. But if you enjoy the book, then read and buy the book. And if you don’t, then don’t. And if you’re uncertain, it’s completely your choice to make either way.