I doubt it at this stage. The deal isn't expected to start until early 2019 so it sounds like there is plenty of detail to thrash out yet.
It will be interesting to see how it is delivered via the YouView box though. If it is exactly the same functionality as via the normal app then I'm not interested.
However, if the channels appear in the guide (or even better, are recordable), then I may be. The BT press release suggests a tight integration:
BT customers will be able to watch the Sky content seamlessly as an integrated part of the BT TV platform.
I also like to buy my passes as I see fit (from eBay or Zeek), rather than using a regular subscription because it costs less, so personally I would want to retain that flexibility.
Lastly, it all comes down to picture quality because NOW TV maxes out at 720p currently. Will the picture quality improve? Will it even be available in HD?
The flip side of this is the BT Sport app will be available via NOW TV boxes. With Freeview HD, Box Sets, catch up, the main Sky Channels and BT Sport it becomes quite an attractive little unit for £39 (albeit the TV Guide and lack of channel number buttons is shocking!).
I have no idea if this deal will filter down to Plusnet customers, but it's not as if we can't use NOW TV through other devices if we really want to.