Riley Dove,
This gives a good picture of where the P-8 programme stands right now:
P-8A Poseidon - Naval Technology
In many ways it is comparable with where MRA4 was when it was cancelled, with 5 development aircraft still apparently undergoing testing and development, and low rate initial production of aircraft having commenced.
The first Indian P-8I has indeed flown, as this article illustrates:
Boeing P-8I aircraft for Indian Navy completes first flight - Economic Times
but only a few weeks ago. Also note that the article says that mission systems are still to be installed!
While the P-8 is not a concept aircraft, it is still some way from being an operational, proven MPA. However, if you want new, it's pretty much the only game in town!
I still also believe that if we ordered them tomorrow (which we won't), we wouldn't see them for 3 years!