Samsung GALAXY Note II and the Nokia Lumia 810 will both require software updates to turn on their internal LTE radios. While T-Mobile says that it will be done, the timing is uncertain. Ah, the third phone with possible LTE connectivity is the...Google Nexus 4. The device does support LTE over Band 4 (1700MHz AWS) but this would not only require a software update, it would also require FCC approval which the hard to find handset does not yet have. That means use of the Google Nexus 4 over LTE pipelines is currently against the law. As far as upcoming models are concerned, there is talk of a revised version of the Samsung Galaxy S III that will be LTE enabled, and of course the big news hog of Wednesday, the BlackBerry Z10 will also launch with LTE connectivity.
If you live in one of the cities we mentioned earlier, you might want to consider looking at an LTE enabled model soon. Otherwise, you probably have time left with your current phone, enjoying the still fast HSPA+ 4G that T-Mobile provides.