The usual advice is: if you can wait, wait. If you can't, then buy it now and put it to use.
The end of October is usually when we hear about new iPad releases, with November being the time when you'll actually receive it or be able to buy it. iPads are in fine supply most of the time, too, so there shouldn't be a concern about having to wait an additional month or two to get one (like you do with iPhones). It's not a particularly long time, so I think it's worthwhile to wait. If the rumors are true and the iPads won't actually be refreshed until the spring, then you can decide if you still want to wait. But it'd feel silly to buy an iPad mini 4 now, only to find that an iPad mini 5 came out in one month, right?
As to the rumor that Apple will be discontinuing the iPad mini line, it's been kicking around for the last 2-3 years now. I certainly hope it's false... despite Apple giving is lesser hardware than the other iPads, it's the ideal size for the mobile professional. If Apple released an "iPad mini Pro" with Pencil support, I'd gladly buy it even if they upped the price by a fair bit.