What is causing my engine to burn so much oil? How much longer will the car last

What is your question?

I have a 2008 Scion TC with about 170000 miles on it. Everything has seems to be in running order, except the issue of burning oil. It started off as something small with normally I'd have to put a quart in every month. It's gradually gotten worse, and in the past 10 days I've put 5 quarts in it. I'm driving around 200 miles a week to cause this, and I'm not driving her hard. Any suggestions? Should I start looking for a new car? Will it be okay if I keep running it as long as I keep filling it with oil?