A very quick post...
Apple is now in an extremely happy place and unusual place. It has worked out a magic formula (big fan base, good products, expectations of pricing), where it can pretty much guarantee that it can earn at least $200 of gross margin on any mid-to-high end product it sells - iPhones, Macs, iPads and so on.
So as long as there is a decent-sized market, at low enough risk, it can afford to treat certain new things as "projects" even though they may not be game-changing. If they do change the game, even better.
For example - the iPad. Even if it only sold 10 million, Apple would be up perhaps $2bn in gross profit. Even if the R&D upfront was $500m, that's still a pretty decent return.
And so now, everyone is talking about a Verizon iPhone. A year or so ago, I would have been skeptical - a CDMA iPhone would have been a risky distraction. Now... with an extra year's traction, it seems like 10m units is pretty much a baseline. And I'll assume the cost/profit structure will look pretty similar to the HSPA ones.
In other words, it's money in the bank, assuming that nothing goes horribly wrong. The only argument against it might be the opportunity cost - could those engineers be doing something *even more profitable*. But I'd imagine the company has had the time & resources to get its hiring aligned with its business opportunities.
By the same token.... could Apple make & sell 10m LTE iPhones, at $200+ gross margin, at equivalent low risk next year? No. And probably not in 2012 either. There's not an installed base of existing customers to sell to, the technology isn't mature, the chipsets expensive and the user experience would likely have issues that would mean something "going horribly wrong" would be much higher probability.
If it can stop its margins creeping down, I'm sure there are plenty more alternative 10-30m unit segments that Apple can target for its next few billion, while it's waiting for LTE to make the cut.