It is a very hard question to answer as it will depend very much on you and your useage, miles alone don't tell the whole story, that said your cleaning regime needs improving, once a week is not enough IMO, a quick wipe of the rim and brake block after every ride with a thorough weekly clean would be much better and not much more effort.
In my experience and the sort of use I get from rims, if a pair of rims had worn out with the mileage you have had, I'd be contacting the manufacturer and telling them the product was either faulty or not fit for purpose. In fact I recently did this with Pro-Lite after a rim wore to the point of cracking, in what was, in my experience, a disgustingly short amount of time. This was after 3k miles at most, more likely ~2.25k of mostly dry riding, relatively little braking as I don't commute and bar a few traffic lights on the way to my training routes, I only ride to train on uninterrupted routes and clean my bike after every ride (they tried to tell me I had done more miles than that, but I know better as I log things in such a way I can deduce the actuality within a pretty good range) but for you and your riding style, cleaning regime, where you ride, etc that mileage way well be completely normal and acceptable.