If you think of your P4 as a stock, which you shouldn't, it just took a hit with the release of the Mavic.
Once the community realizes that they are two different things, the price will probably go back up. As a reseller, but not an authorized one, I can tell you that everything from the birds themselves to the accessories all have major fluctuations in price.
As I have said many times, there is a sect of the P4 community that wants the Mavic and losing that group is not cannabizing because they want a small form factor.
A perfect example is I like to fly my Phantom over my Inspire because I enjoy flying it more and it's smaller and both are toys because you can't deliver broadcast quality but they are professional to the person that wants the Mavic. I want the Mavic by the way, lol. But I want everything.
Either way, the Mavic isn't for the P4 user, it's for the Mavic user of which some P4 people are.
Or you might have a place for both.
Real world example: I am going to Carlsbad with my family tomorrow for the weekend. I would rather bring the Mavic than my P4, Inspire or H but the P4 is coming but not if I owned a Mavic or a wife who was more into the UAS world.