There will be a Verizon iPhone 5 as soon as there’s an iPhone 5, but those on Sprint and T-Mobile will need to hold their breath and keep guessing. While the Verizon version of the iPhone 4 arrived more than half a year after its AT&T iPhone 4 counterpart, that was a one-time occurrence thanks to the eschewing of the much maligned Apple-AT&T exclusivity deal. Now, when the new iPhone 5 comes, it’ll be guaranteed to arrive on both AT&T and Verizon at the same time. The only question is whether it’ll come in a single unified model which can talk to both carriers’ incompatible networks, or whether segregated iPhone 5 models will still be required.

But the prospect of a T-Mobile iPhone 5 is a different story, as the carrier has bet so big on 4G that it seems unlikely to take on the new iPhone 5 unless it has 4G, which is a big unknown, and Apple of course isn’t talking. An iPhone 5 on Sprint faces the same scenario, as the carrier has also bet big on 4G. Sprint also faces the challenge of having no (known, public) existing relationship or deal with Apple of any kind, leaving Sprint on the outside looking in, at least as far as any outsiders know. T-Mobile is in a different yet equally challenging position; it’s in the early stages of becoming part of AT&T via merger, and it’s not clear whether that merger will be complete in time for the iPhone 5 launch or at what point AT&T would want the iPhone to expand to its would-be subsidiary.

The questions keep coming, but the bottom line hasn’t changed: if you want to be in line for an iPhone 5 at launch, land thyself on AT&T or Verizon between now and then so as to ensure being able to get one. Or if you’re attached (contractually or otherwise) to T-Mobile or Sprint such that you’re not changing carriers under any circumstances, then prepare to sweat out the prospect of iPhone availability until it arrives. Here’s more on the iPhone 5.