Reasoning through my 2008 w/ 125k miles

Hello Priuschat - it's been a while.

My 2008 has 125k miles and runs well. It has cost me very little to maintain over now six years of ownership, and I think I've done so fairly well. I'm starting to get nervous about how much time the car has left, though. I have also moved to a new place where I can no longer work on the car myself.

Things that bother me:

• The car is 17 years old and I know the original hybrid battery will probably unceremoniously fail on me sometime in the next couple years.
• It burns a little bit of oil and leaks a little bit of oil, maybe a quart per 5000 miles. No oil on the ground but can see a bit on the back of the block when the car is on a lift.
• Some dings on doors and bumpers, some clear coat peeling on the spoiler.
• The car is on factory brakes and suspension and probably will need expensive work on either or both soon.

Things I know the car needs:

• I did the P1121 coolant valve myself, with an aftermarket part, which is now making washing machine noises. Additional consideration is that the aftermarket part isn't causing a CEL, and the car passed smog. Luscious/Earthling wants $800 to redo it.
• Rear drum brake is squealing when the brake pedal is released, which I'm guessing would probably be solved with a quick bit of brake grease, but I'm sure I'll have to pay handsomely to have anyone even look at it.
• Spoiler needs to be repainted. Cosmetic only I suppose, but I want my car to look nice.

I make decent money now and could buy a 2019+ Prius or even a new one in the next few years. I am just trying to reason through how to make the most of the time I have left with my 2008. Invest in maintenance and repairs and hope for a longer life? Save the money for the next car and just drive until it won't go anymore? Sell the car now and get into something new before it hits the steep decline?