I'm cautiously optimistic, and I believe Microsoft is taking the long view with their own phones.
I'm optimistic because I believe Microsoft will be adopting the Surface (or Apple) style of strategy from now on. Different market I know, but let's look at the Surface. It took a while for it to get popular, and since the Surface Pro 3 came out, the Surface line has had a small, but strong and very loyal group of fans. Does that remind you of anything else in the tech world? I'll answer that for you; Apple computers. Apple for decades has had a low marketshare in the computer market, yet they have always had a very loyal fan following. The Surface is almost in a similar situation with tablets at this early stage. Small marketshare yes, but highly praised devices and a very loyal following of fans. This group of loyal fans has become influential enough, that AT&T and T-Mobile are about to start selling the Surface 3 LTE (in addition to all the regular places you can get Surface devices from). So that is an example of organic growth. That means Microsoft was in no rush and had zero desperation to sell Surface devices. Purely through the merits and strengths of the Surface devices themselves, and marketing, Microsoft was able to reach this point. A strong enough point, that in this case it's highly likely carriers approached Microsoft to work out a deal to sell the Surface. Also as far as we know, other than being locked to AT&T or whatever, the surface devices that some of the carriers will soon be selling are otherwise identical to the fully unlocked Surface devices you can buy direct from Microsoft. Does that remind you of anything else? It should, as that's exactly the same strategy and approach Apple has used with the iPad.
Now for those of you familiar with the smartphone market, you'll remember that many years ago when the iPhone first came out, it was only initially available on one carrier in the US (AT&T), and that was the case for a couple of years, until more carriers agreed to carry it. So during the first couple of years on the market, why did other US carriers refuse to carry the iPhone? Simple, because Steve Jobs and Apple had high demands for any carrier wanting the iPhone. They could not muck up the phone with any bloatware, or otherwise make any modifications to the phone. They also had to sell the phone at pre-determined prices from Apple, and were not allowed to modify prices outside of Apple's permission. Finally, they had to buy a guaranteed number of iPhones from Apple, before Apple would even allow that carrier to carry the iPhone. So initially most carriers balked at these demands. Soon though, it became obvious that iPhone's small, yet strongly loyal following was becoming too influential for other carriers to ignore. So other US carriers ended up with no choice but to accept Apple's demands.
Now let me come back to Microsoft's situation. The word is that Verizon will be dropped as a partner carrier by Microsoft. Now imagine if ONLY AT&T carries the new Microsoft flagships in the US, or only one of the two flagships. Yes, it will be bad in the short term, BUT it's a good thing LONG TERM. If Microsoft with their future phones is able to establish a strong, loyal following like the Surface line, and right now completely void any existing US carrier relationships that are not beneficial, then they would be in a good long-term position. Then that would mean eventually the strong following of Lumia or "Surface phones" would become too influential to ignore. Then instead of Microsoft caving in to carrier's demands, the carriers would have no choice but to accept Microsoft's demands, were they to want to carry the devices.
As some of you mentioned, Microsoft has other options, like offering 3rd-party financing at their stores. Or they could bundle their phones with the Surface tablets, as sort of special packages at certain points of the year, to help sales.
My main point is, iPhone sales originally started small, and grew organically, without any forced pressure, until it became impossible for other US carriers to ignore the iPhone.
My main hope/belief is that Microsoft will follow this strategy.