The new Twitter still supports 3.5 inch displays, for now (Dribble)
Analyst predicts that the iPhone 6 will have a 4.8 inch display. This wouldn't be too surprising, as the change in size releases (iPhone 5, iPad Mini) have followed about a 2-year release cycle if this would be accurate. 2 lines of phones would make sense, and the C and S might drop from the title. The iPhone S may be the bigger model, while the iPhone may keep its 4 inch display. This change could take away the need to develop 3.5 inch applications and go to developing 4.8 inch display applications. The release wouldn't change mostly anything, but the 4S still being sold may halt more development until Apple runs exclusively on 4 inch or more displays. How all of this will play out isn't yet clear, but once Apple makes a move to a larger display, developers move along with them. Removing screen dimensions isn't an option for a developer, and Apple doesn't seem to be taking any steps back from their designs so far (besides a few Macs) and they have done so not purposelessly.