Purely speculation, but I expect to see a colour version within a year or so. There is a big price gap between the current ProntoPro and the iPronto, not to mention that they are very different concepts of what a remote control should be. As long as the current ProntoPro has sold well, I think there will eventually be a redesign.

The fact that you can import colour bitmaps into Prontoedit NG and it retains the colour on the editing screens and downconverts when it sends it to the remote or the emulator may be a hint that a colour version is eventually coming.