https://forums.macrumors.com/threads/530728/ there is this topic here too... i'll just copy paste what i said:
Ok, here is my statement.
For those who say there won't be an ipod touch on the next keynote... i don't believe that... some of the stores are already making new prices and since they have to do something with the other two ipods and since they've remade iphone already and are about to launch the new computers too... it lacks ipod touch! ipod touch will suffer anything.
Steve Jobs has to do a something different. All of we know that everytime he launches anything it has something to make us just go
So... there will be difference!
Where? From common sense i may say it will launch gps, gps is like a simple chip, for them, it won't cost much and since they sell a lot of iphones/ipods they must have a standard logical board to get more profit! So, for me they will take the iphone's logical board... it wont have 3g of course because then they could have phone and iphones would lose but more certain... gps chip! that i think it will really have.
Other thing about... camera! Since they will use (on my sense, not a fact) the same logical board... they won't lose much on the camera! I think that that won't affect the iphone. Iphone will always be more expensive and then other thing... people buy iphone so they don't have to carry a lot of stuff on pockets. So the difference should be on 3g and GSM, camera won't affect! There must be a low price choice for the people! Camera is a positive point!
Apple always redesign their stuff... so... maybe a simple one but... there will be, maybe a reduction of size! not much but some so they can present more stuff on the keynote
I think these are the changes! Please refute if you think i'm wrong.