I would rephrase it to be "Where did anyone get the assumption that there will be NO mavic pro II or any new enhanced mavic".
just look at dji site, it's all series. Phantom series, Mavic series, Inspire 1&2, Osmo and Osmo2.
dji will die if they don't keep producing new and enhanced product as per their customers demand.
That's the most basic rule of business. Look at apple, Samsung, car manufacture and the rest business world.
With regard to buying choice, I would read the market and make the choice that suites me. Since I already have the MP, I would definitely wait for something better. If you are a beginner and never had a drone before , I would recommend the air or the spark if you don't want to spend more than you need to.
You are 100% correct, only thing I hate is the more enhanced it gets the more faults that seem to arise in the software....yes I would love to see a Mavic Pro 2 (or what ever name it will be called) actually the more I look at the Mavic Pro (yes I have one) the more I want too see it being produced with updated and better options, after all, everyone loves the Mavic, its a great little Drone that can fit into just about anyones style of usage.