NVIDIA had the 4.4.2 update ready to roll out to Tegra Note 7 devices over four months ago, which is when it rolled out to the EVGA Tegra Note 7 (among others). The HP Slate 7 Extreme – which is virtually identical to other TN7s – has been waiting ever since. And finally, today, that same update started rolling out.
I guess it's better late than never, but it's still pretty clear HP dropped the ball here (surprise!). Oh well – at least you're basically up to date at this point, Slate 7 Extreme owners.
Head into Settings > About tablet > System update to pull it now.