Yes, the switch just unplugs from the main harness and the Key-Less plugs in, in its place. If the switch is left mechanically in place (but disconnected electrically) it can still retain the fork locking function if desired. (My switch is removed completely - I use a disc lock for overnight parking when on road trip)
If replacing (or repairing) an ignition switch, then additionally a headlight-bypass relay kit should be employed to prevent recurrence of the original problem - replacing the switch ALONE is only a temporary repair.
The KeyLess system does not have the failure mechanism the switch experiences - a bypass kit is not
necessary, but can be added at the users choice (or left in place if they already have one).
With either switching device, the headlight relay kit will give a bit of headlight performance improvement on a classic with incandescent headlights (as well as preventing further damage to the mechanical switch if retained); I would instead suggest putting the money saved on a headlight relay kit to some good LED replacements - a headlight relay kit will make zero difference to performance on those - they will also reduce the current by close to half (putting more in line with the Touring model with only one incandescent headlight and those rarely fail)
The absolute big no-no is to run high-wattage incandescents - that will make accelerate failure of the key-switch.
Kits are built to purpose with the appropriate model/year connector (I have come across a few with a late model connector that was spliced in to main harness, but these are relatively rare)
This is indeed
often repairable - the wire detaches from the wiper plate - because of poor connectivity, the soldered joint heats up and eventually lets go (or fractures with tension/vibration) - as long as the solder pad on the wiper plate has not been compromised the wire can be resoldered into the pad. As
@Gregger says, removing the switch would be the most time-consuming part of the process - I would suggest not actually removing the switch but remove the Top Triple Clamp and invert to access the electrical part of the switch - remove the bottom access cover.
And again, after a repair take some other remedial action to prevent further recurrance (relay kit or LEDs)
Anyone who wishes to convert to KeyLess should
only do so for its own merits (it will of course eliminate any future problems in regard key-switch failure) - in terms of a repair option, the advantage would be (as well the benefits of the Keyless itself) that it is essentially a plug n play option that most anyone can do - replacing the key-switch requires a lot more work (the aforementioned old switch removal process). Plus doesn't need the added cost of the ByPass Relay kit. But frankly, in all honesty, it's a not an inexpensive option for repair.