Actually quite a good idea, although the additional A/D conversion doesn't matter in a live scenario.
And as most users prefer their own solution (and some don't want wireless at all), I'd say it won't happen... 
Yeah, too much of a niche IMO too...
What we really miss IMO are standards, and commercial agreements among the big guys out there.
Ideally, any charger would charge any phone, any two analog/digital devices would talk to each other via a simple connector, any computer would use the same standard communication ports and protocols.
Disgressing a bit, am I not...
I don´t think that this will ever happen for two reasons:
1. The users that prefer a wireless solution often have already a system running. And these things often cost at least half the price of a KPA. Of course there a many solutions available at lower costs, but these are not the ones to rely on IMHO.
So if you put that inside the KPA it would cost much more (IMO based on the additional cost of a powered KPA vs the unpowered)
2. Most users will not need it. If you are sitting in front of your DAW, you simply do not need a wireless system.
That will be the main reason if i´m right. Nobody needs wireless in the studio where you are placed near the unit.
I am using my wireless guitar system and my (also wireless) inear system at home because i like to walk around while playing and i often do this at night.
My neighbors haven´t noticed yet that i´m a guitarist 
Thats a nice-to-have, but i could also sit in front of the KPA with a wire and headphones with the same result. 
There are wireless systems that have digital outs, e.g. that huge Sennheiser Digital 9000, which uses AES-outputs. I think and hope we will see those units become cheaper and more useable for "normal" users like most of us
I'm right now fantasizing about a 1u rack unit, that contains a wireless receiver and an iem transmitter with digital (spdif) ins and outs to connect easily to the Kemper. It also could have 2 or more xlr/trs-inputs for a monitoring signal from FOH, which can be mixed with the signal of the Kemper. And not to forget a iec 320 in AND out to power the Kemper, so you won't need those ugly cabling in the back of your rack 
If someone (Kemper? 
) will develop that unit, I would nominate you for the Nobel Prize
Just my two "humbled" cents
Stefan
It doesn't make sens for us to enter the market of wireless systems, as this is a complicated topic, and other companies do good work.
However, they have missed yet to implement a digital output (spdif) to their receivers, since they probably don't know too much about the propagation of professional digital guitar amps of today.
You should definetely do some noise on their websides to show them how many you are.
A spdif connection to the instrument in would bypass an analog conversion at a point where it is the most sensitive.
This.
It doesn't make sens for us to enter the market of wireless systems, as this is a complicated topic, and other companies do good work.
However, they have missed yet to implement a digital output (spdif) to their receivers, since they probably don't know too much about the propagation of professional digital guitar amps of today.
You should definetely do some noise on their websides to show them how many you are.
A spdif connection to the instrument in would bypass an analog conversion at a point where it is the most sensitive.
YESSS
