T-Mobile has shown that they can be an effective mobile competitor to AT&T. However, it's unclear how long that can last. With 5G, home broadband and entertainment is likely to come into play in a huge way.

Let's fast-forward 3-10 years to a 5G world where we ditch cable companies and get pay-TV, home broadband, and mobile from a single company. AT&T and Verizon have deep millimeter-wave spectrum holdings. T-Mobile is likely trying to acquire more, but they're at a large deficit that might make 5G much harder for them. Likewise, Verizon and AT&T both have established pay-TV businesses they can leverage toward a 5G home broadband and 5G pay-TV future. Heck, AT&T bought Time Warner knowing how important this would be. T-Mobile knows this is going to be important and is making investments, but they're smaller with a smaller customer base.

T-Mobile's size and lack of ownership gives them little power in negotiations with direct competitors. Comcast will drive a hard bargain for their content as T-Mobile looks to replace their wired connections. AT&T has little reason to offer a good deal to their direct competitor. Even independents have little reason to offer a good deal because T-Mobile's smaller customer base leaves them in a weaker negotiating position.

Likewise, AT&T and Verizon have a lot of revenue to invest in a big home broadband play compared to T-Mobile. They also have large customer bases to up-sell home broadband to. AT&T has already shown that bundling can be a big deal. If AT&T starts offering home internet as a $30-add-on for their mobile plans, that creates a lot of lock-in. Not only could that make it hard for T-Mobile to break into the industry, but it could even kill off T-Mobile's mobile growth and start customers flowing back to AT&T for an attractive bundle.

Again, AT&T has the millimeter-wave spectrum, the content ownership, the fiber network and internet backbone, the large customer base to up-sell, lots of TV experience, local installation technicians from DirecTV, etc. What does T-Mobile have to compete with this? Well, better management and maybe a more trusted brand. Given AT&T's content ownership, they could really provide a compelling bundle that might be hard to compete with for a smaller carrier. Verizon is large enough that they have enough power and they already have most of the other advantages AT&T has.

So, yes, T-Mobile has been doing well. Will they continue to do well? Are we at a point where the industry is changing to not-just-mobile? Have we created a great competitor for what consumers are looking for between 2013 and 2022, but aren't looking to what consumers will demand past 2022?

Heck, Cingular and AT&T Wireless merged and spent a huge amount of time and effort creating a reliable 2G voice network...just to see the industry shift off of voice. I think T-Mobile has done amazing things, but it's definitely possible that industry shifts over the next 5-10 years will provide new challenges for T-Mobile. Do we have a great competitor for the next couple years, but a duopoly as the industry shifts after that? T-Mobile has "proven they do not require a merger to be successful" in mobile wireless. That might not be enough going forward.