T-Mobile antics are a two-way street. They have come out and said that their plans will either bring them lots of customers or force the industry to change. Well the only ones that have really changed are AT&T. Sure Verizon and Sprint did their "early upgrade" programs, but AT&T is the one that is steadily changing their plans to make them cheaper. In fact, this past weekend they announced that you can bring your own device to AT&T and pay $65/month for unlimited talk and text with 2GB of data. That's a pretty good deal actually.
On Monday, Re/Code reports that Verizon's CFO Fran Shammo who is at a Deutsche Bank technology conference today, that he wasn't at all worried about the price wars going on between his competitors AT&T and T-Mobile. Stating that aggressively undercutting your competition's prices is self-destruction in the long run, and he's speaking from experience. "We're not going to buy customers" stated Shammo. "You have to earn customers."
Basically what this tells us is that Verizon isn't scared of T-Mobile. Verizon knows they have the best mobile network around in terms of reliability. While AT&T has the fastest network. Verizon has been #1 for quite some time and add millions of customers each quarter. So that they don't have a whole lot to be scared of. Speaking of numbers, Verizon's Q4 2013 numbers consisted of adding 1.6 million new postpaid customers, and making that 4.1 million for the entire year. That's close to what T-Mobile did in 2013, but the difference is T-Mobile ARPU has dropped, while Verizon's is still pretty high, meaning they are making more money per customer than T-Mobile is.
I don't see Verizon budging much until they start losing customers, which probably won't happen for a while, especially those with unlimited data on Verizon. I also don't see that happening until T-Mobile starts utilizing that spectrum they just bought from Verizon, and that might even be a stretch.