Sounds about right. There are coatings that can be applied, with risks that come with it.
Personally, I wouldn't bother with anything more than the coatings that come on fabrics. The risks of getting sticky, tacky, stiff, or yellowing are worse to my mind than the effect of fading due to age. Of course, I also have a small stock of Icarex / PC31 fabric that is coated, and UV-treated thread. Many kites are built from the stuff, but some are not.
Ultimately kites are meant to be flown. Fly it, love it, let it get the UV damage from sunlight, damage from flapping in the wind, and when it's eventually battered and weathered and worn, retire it. If you're flying it enough that it is damaged due to wear and sunlight that means it's a well loved kite.