There are several components that will get worn and eventually need replacement no matter what kind of oil change regiment or maintenance you perform.
Here's a short list.
Engine
Rings - Your rings are moving up down with the piston as the engine runs. This will wear them regardless of the lubrication. You can extend their life by not revving the engine to higher RPM's and mitigate wear with frequent oil changes but at the end of the day it's metal on metal contact therefore they will wear down.
Cylinder Bore - The rings moving in the cylinder bore will wear down the cylinder bore over time. Exhaust gasses will begin to slip by the rings reducing your power and fouling up your oil quicker over time.
Transmission - From shifting, your dogs and slots will wear down and become rounded. This could take decades or months depending on if you are shifting properly.
Valves and Valve Seats - Poppet valves are banging on valve faces on the head at half the rate of RPM's. That's a lot of banging. At some point in the engines timeline valves will need replacement and the valve seats will require recutting to mate properly to the new valves. As well, valve guide seals are rubber and will become hard over time with the many heat cycles an engine will go through over it's lifespan.
Drivetrain
Chain - Your chain will wear. It's exposed to the elements. It transfers all the power to the rear wheel. It's a consumable and viewed as a component that will require several replacements over the life of the motorcycle.
Sprockets - Sprockets get changed and wear with the change. They are consumable as well. Like brake pads, they wear out and become 'mated' to the chain. Always replace chain and both sprockets at the same time.
Suspension
- Forks and Shocks - No matter how nice you are to the bike eventually shock and fork seals will fail. I've had some last 15 years and other last 6 months. As well, fork oil requires change and it's recommended to do the fork seals at the same time.
Conclusion
All vehicles experience wear no matter how well you take care of them. Eventually, given enough time, components will fail. Coils will wear out and degrade. Fork tubes will wear down over time. Brake pads and clutches will be consumed and replaced. It's an unfortunate reality we must all endure.
Edit
If you are experiencing a degradation performance there are few things you can check.
Fuel Filter - Ensure your fuel filter is flowing properly. If you have good power off idle and then it degrades shortly (within 15 to 30 seconds) it could be your fuel filter is clogged and not feeding the fuel system properly.
Air Filter If you air filter is obstructed due to use you can have significant performance issues along the entire RPM range. Ensure the air filter is changed on a regular basis to prevent debris from inhibiting air flow.
Valve Adjustment On shim and bucket top ends the valves slowly begin to take up clearance between the bucket head and the cam lobe. I have had motorcycles that are at zero clearance and once you get them hot, they won't run because there is a valve hanging open. Once the bike cools, then it starts. Before the issue get's that severe the bike will lose overall power and appear sluggish. It's a regular maintenance item that should occur according the manufacturer recommendations. I adjust the valves on all my bikes, once every six months just because I don't mind doing it and I'm usually teaching someone as well. You don't need that kind of fervent frequency but it is recommended to have this performed as a regular maintenance item.