I wouldn't worry about the miles. Age affects Volvos far more than miles. Where I worked, Eurocars Plus in Connecticut, we regularly sold cars with that kind of mileage WITH A WARRANTY. I don't mean the state mandated "30-day" warranty. We performed complete by-the-book service and put these cars on the road with a 12 month/12000 mile drivetrain warranty, and a 90-day/5000 mile bumper-bumper warranty. We couldn't do that with any other kind of car, I don't believe.
A few items need to be replaced for certain to achieve reliability at this age:
1) Fuel pump relay
2) Engine speed sensor
3) Regular timing belt service (yours should have been new at ~ 150K, due again at 200K
4) Cooling system - no leaks, replace original radiator if it hasn't been yet
5) Transmission service + tailshaft seal
6) "The usual" stuff any car would need: brakes, tires, exhaust, front suspension parts.

If these needs are addressed, the car will be fine for a long time for you.
I'd expect another 100K out of it, absolutely.
BTW Eurocars still sells Volvos with that warranty, but they do limit what they sell to 10 years old now. The newer ones are proving just as reliable as the older ones.
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Rob Bareiss, New London, CT 86 244, 87 244, 88 744