Probobally pretty short. But we have documented pings discharged at that rate lasting a year. I sure don't recomend it, and sure don't recomend any examples of pings standing that 2c discharge for years and years. Most of those I recall reading about were because the battery was no longer working right after a year of such abuse. Often enough less than a year. Not all of the batteries were pings though, some were the cheezier 18650 cell packs. Those are 1c cells.
2000 miles or less would be my estimate. You could of course get lucky. It's a matter of the odds that one of the pouches in the pack is not as robust as the rest. Just one pouch gets weak, then the whole pack is 5 ah smaller in capacity. Soon an entire string of 4 paralelled pouches is gone, because once one goes, the others get higher discharge rates. The basic problem is getting lucky enough to get a pack with every single pouch in it very strong. It does happen, but there is no garantee your pack is so lucky. More likely one pouch in there is only OK, rather than exceptional.
Trying to explain, you are promised 2c cells. Likely all your cells can handle 2c for awhile. But the discharge test for the cells is performed at 1c or less. So you push 2c from all your cells as you are doing, and they won't last the 1000 cycles at all. Lucky if you get half that. Likely enough to get less than half the 1000 cycles. Then if you get one cell in there that is really only able to stand 1.5c, and you might puff up that cell even sooner. You just can't expect maximum lifespan from your cells if you discharge them at the max rate. The rule of thumb I use is cut the c rate almost in half, so you'd consider your pack good for at most 30 amps, and conservatively, 20 amps.
It's true though, it depends a LOT on how you ride. Obviously even if you have a 40 amp controller, riding 20 mph is not straining those batteries. But I bet you do use about 20 amps or more going 40 mph, and for sure you spike it to nearly 60 amps starting up if you grab lots of throttle.
I know of one example of some pings running on 30 amp controllers, and doing fine. But I'm not so sure they are ridden hard. They might never be getting more than 1c, even with a big controller if the rider does not like riding fast.
