Roku, obviously, is on the leading edge of streaming devices and will undoubtedly be there to help you stream mainstream TV when the time comes. In the meantime, it can give you a lot of content for the money, whether you're watching stuff in 480i
One of the leaders in the "smart set top boxes" market has expanded its line so it now ranges from extremely affordable to extremely capable - not that each category is mutually exclusive.
It's Roku, whose line now stretches from the $39.99 entry level Roku Express to the $139.99 Roku Ultra, the latter of which will output in 4K, giving you state-of-the-art video from a small and affordable package. Naturally, you won't appreciate the 4K aspects unless you have a 4K TV, but even if you don't yet have that type of video you can output it at whatever resolution you have now and it'll grow with your capabilities.
Roku's line actually features five new players - Roku Express, Roku Express+, Roku Premiere, Roku Premiere+ and Roku Ultra - as well as the Roku Streaming Stick I reviewed and liked so much several months ago, which now sits somewhere in the middle of the Roku line and is positioned as a portable solution (and for which it's eminently suitable).