I have 168,000 on my 124 2.5 turbo and it feels like it will run for another 150,000. This is the work I have had to do over the past 35K:

Replaced:

Fan belt, clutch and tensioner
Front struts - Bilstein HD's
One transmission cooler line
Radiator, hoses and thermastat
Antenna mast

Work needed:

New tires
Refinish rims
Left tie rod end

General maintenance:

oil ever 2.5K
oil filter every 5K
trans, rear axel, fuel filters, PS fluid, brake fluid, air filter ever 20K

You will have repairs. Wear items will wear - like on any other car. The car as a whole will last for several years and hundreds of thousands of miles if maintained properly.