It is very unlikely that the original hoses will suddenly fail at ages less than 15 or 20 years unless the hose had been subjected to abrasion, cutting, or severe stretching/bending while working on the car.

The mode of failure is usually loss of rigidity allowing the hose to 'baloon' under pressure so that the prake system pressure is not complell transmitted to the caliper - result - soft pedal. The other potential mode of failure is that the inner liner of the hose becomes soft and collapses inside the hose - the brake system pressure is transmitted to the caliper, but when the pedal is released, the hose collapses and acts like a check valve keeping pressure on the caliper - result is dragging brakes, overheating and warped rotors, and exccessive rotor/pad wear.

You can buy the IPD DOT approved stainless braid brake lines for about the same price as the Volvo replacement parts.

Replacement is straightforward EXCEPT that you need high quality tubing nut wrenches and you should soak all fittings with good penetrant like PB 'Blaster' or 'Kroil' several times for a week or so prior to trying to remove. This may save some of the fittings and hard lines that you might otherwise have to replace due to frozen fittings. After replacement, the entire brake system will require flushing/bleeding (Use pressure bleeder like Eezibleed).