There is no TV movie, that was a rumour.
My initial reaction was to be a bit disappointed, like "that's it?
" But the more I think about it and reflect on it...that was pretty much the way that show should've gone out. It reflected more or less the overriding themes and issues of the series as a whole, and it even left a little bit to the imagination.
BTW at the end they said Gunn had about 10 minutes to live. So you can assume he died in the battle.