I, myself will not. I was already forced to buy them all a second time when the iPad came out. I'm fed up with the double (and possible) triple dipping.
I'm hoping all apps will be compatible. I can't imagine Apple making every developer update their apps. I hope that there could be a status bar to take up the rest of the space of the new screen. That bar could include things like sports scores, weather, setting toggles (wifi, airplane mode, etc.), texts, emails, etc.
But I think I would jump ship to Jelly Bean if I had to repay for all my apps.
Aside from very few games, overwhelming majority of developers did not charge for retina iPhone 4 update. I expect the same for new iPhone.
I, myself will not. I was already forced to buy them all a second time when the iPad came out. I'm fed up with the double (and possible) triple dipping.