It has been coming soon since before the P3... There is also a difference in "how". The Solo is based on open source (PixHawk and Ardupilot) which means people can change and add to the programming, sensors, hardware, etc. etc..
DJI is a closed system based on NAZA and has only an API. It doesn't mean a lot to people now. But it is the equivilant to MAC vs PC... Upgrades on PC's exploded. No so much ffor MAC's
DJI knows this, except in this case, they can't easily claim the high end with new products, as they already did that with Inspire and Matrice, and with such bad service they don't have Apple like "customer experience" so they will go cheap and will try to compete on price. They will come out with something cheaper... You watch. Still not "upgradable" though. The idea is to buy a new one every year... No thanks.
Update... Ooops. Saw the link and the new "standard" model.. I knew it