To answer your question yes in simplest* terms. Nothing can not be repaired sans catastrophic destruction of the vehicle frame. Look at the life spans of US Weapon systems ... Carriers, B52s etc. In reality maintenance to that level would approach if not exceed new car value for me. I am a perfectionist when it comes to automotive care.
The key is though how much money you want to sink (due to depreciation realities) or invest (if you are that optimistic) into your equipment. Weapon systems costly as they are go through service life extension programs (SLEP) and are gradually updated over time.
Yes parts will inevitable fail over time. The question is will you keep up with repairing and replacing them. I am confident my engine (3800 Series II) may make it too 250-300,000miles. However, I am not confident my 4L60E Hydramatic transmission will make it to 250,000 ... and if it does consider me a lucky man statistically! Already my 10-bolt differential is making whining. There is also the exhaust system which is showing some corrosion, much of the front end is original. However, inevitably ball joints and weathered rubber bushings will need replacement also.
Now let me do the Department of Defense and FAA way of getting my car to a million miles. I am at nearly 200,000 miles right now. A basic life extension would be to reman the transmission, and differential (4000$+). I could throw in a repaint as well (4000$) and repair interior broken trim pieces (400$). The engine I could leave alone until 250,000 - 300,000miles. However by then I would likely need frame off work and sandblasting to repair and seal corrosion issues. Even if it did all these things my drive train would be bought time until 500,000 miles when possible additional "engineering level" maintenance is needed.
So yes I could do it on my car .... but it would break the bank and doing so would be madness. Also as mentioned earlier I am not in a taxi or fleet situation. My annual mileage is 12,000-18,000 miles per year. I calculate it would take me 46 years of daily driving at present rates to achieve the 1-million mark. A lot can happen in 50 years
My car would be a museum piece and lightly driven if my intention was 5-decades of ownership.