I'll have to admit, even with the metric **** ton of characters we have in the series, those who don't pull their weight won't appear. We have a fair bit going on in the background, and there are going to be off-shoot stories and short pieces in between the main books. The majority of that 400 will make onscreen appearances, but if they serve no plot purpose at some point then they'll either be cut or they'll make their debut in a later book.