Radios Converting to Digital?

| Will the conversion to digital radio effect RC modeling?
You mean like HD radio and digital TV? (I'll assume you're in the US. If not, replace 72 MHz with your country's band, and FCC with whatever your country's equivalent is.)
If so, then no, not at all. Apples and oranges.
If you mean spread spectrum R/C, usually on 2.4 GHz, that certainly affects R/C but it's not really a conversion but instead a band/modulation that's supplementing the existing 72 MHz band. It's not really a government/FCC thing, but just new equipment becoming available in the last few years.
In the next few years, I'd expect to see sales of new 72 MHz gear drop to almost nothing (and it's already well on it's way) and people to instead buy spread spectrum gear. As for used gear, people will keep flying their 72 MHz gear but over time it'll be used less and less as well. And perhaps somewhere down the road, the FCC might want to reallocate that part of the 72 MHz band, but I wouldn't expect this for at least ten years and probably not even then, as I'd expect the band to be used a lot more for the `toy' park fliers like you find at Toys-R-Us (which will also help drive the `serious' modellers to spread spectrum.)

Did the change from escapements to reed radios affect RC modeling? How about from reed to galloping ghost and then to proportional? The change from 27 MHz to 72 MHz along with additional modulation methods and receiver designs?
Everything has some affect, most of it good.