sure, a television can work fine. my own system (link in sig for pics) uses a 40" and it has worked out well.
you WILL need to run the tv in 60hz game mode or disable the 120/240hz on some tvs and disable motionflow or whatever they are calling the special features nowdays as these cause lag when dealing with real-time signals.
tvs also arent as ideal for text so you might need to bump your browser zoom or text levels up a bit (even more true on a 4k tv) to best be able to read them but otherwise works out fantastic.
i've been using a 1080p 40" for over 4-5 years now and while it does take some time getting used to it at first due to the size it really does grow on you after awhile.
if you are gaming at 4k you are not going to be using a 144hz panel. i'm not sure if the bandwidth exists on cables yet or not but even if it does you will not get good enough framerates on a single gpu (without running at low settings) to generate that sort of fps. running at 60fps at 4k however should range from good to poor on a single 970 depending on the game. i've seen as low as 26fps on low settings for some titles to as high as over 60 on others at decent settings. generally though 4k is best on multi gpu if you want the best settings.