I don't think the PSP is going to be homebrewable JUST because the motherboard's number is TA-085. Yes it is a smaller number than 86, but that doesn't mean anything. It's obviously a very different board. Things have been moved to completely different places. I don't think this is going to be what you guys are expecting. Maybe Sony is hoping that they can fool people into buying it by making the number 85 and giving them a false hope of immediate homebrew.
Personally I don't think it will be as simple changing the idstorages. There're going to be extra safeguards that haven't been around yet.
Numbers can be very arbitrary things at times.