It seems like this question has been asked multiple times, and it seems like each and every time Harmonix shoots the idea down… at least at launch. This is an example of what @HMXHenry has said addressing it:
There won’t be any Pro guitar upgrades available at launch but we’ve discussed the possibility of releasing a few as DLC at a later date. You can keep posted to future DLC announcements for more info.
But now that the Rock Band Blitz songs are live over on RockBand.com, it appears that there may be evidence that several tracks may see Pro-Guitar/Bass upgrades.
As you can see from the image we captured above, it appears that there are some Rock Band Blitz tracks with the Pro-Guitar/Bass upgrade icon. You can verify this yourself over at RockBand.com, if you want (for a brief time, I’m sure).
We went through all the Rock Band Blitz songs, and noticed the following track with Pro-Guitar/Bass icons on RockBand.com:
- Iron Maiden – Wicker Man
- Kool & the Gang – Jungle Boogie
- Living Colour – Cult of Personality
- Red Hot Chili Peppers – Give It Away
- Rick Springfield – Jessie’s Girl
- Soundgarden – Spoonman
Take this with a grain of salt however, as we have seen Pro-Guitar/Bass upgrade icons on songs over at RockBand.com before, however many rumored tracks ultimately ended up having never received Pro upgrades. In fact, this may very well be an error, as the individual pages for these songs clearly list “No Part” for the Pro Guitar and Pro Bass sections.
[Special thanks to Felix for the heads up!]