No doubt, MSFS2020 is the best Landscape Simulator that has ever been created. Whether it will become a Flight Simulator is (only IMHO) strongly dependent on two factors: 1.) The availabilty of detailed ground installations (including airports) and 2.) the availability of reasonable aircraft. While there are quite a number of airports and cityscapes around (so far the number of installed airports in my MSFS is exceeding 350 and still counting), the downside is the availabiliy of reasonable aircraft.
My personal immersion factor is dependent on both detailed airports and aircraft. I would never land on a default airport unless circumstances require to do so. it's just a number of painted 3D boxes around a RWY system. When it comes to aircraft, things are becoming even worse. The default aircraft all are graphically perfect designed three-dimensional moving eyepoints. To make them behaving like an aircraft is another story. Apart from some low level scenery flight over known and unknown territory I mainly use Flight Simulation for point-to-point IFR flights under RW conditions. While some of the Garmin G1000/G3000 mods are increasing the immersion factor in each aircraft using such equipment, the handling and realism quality of most aircraft is - despite the mods - still considerably low. To name a few: KingAir, Cessna Logitude (incl mod), A320neo (incl mod) which are the kind of aircraft I use for longer range. The lack of a few professionally modeled aircraft is obvious.
Apart from IFR flying I also do quite some online sightseeing flights (at least once per week a full afternoon..
) with a fried of mine, using the connectivity means of MSFS for formation flying and airport hopping. But even there my (personal) immersion drops immediaely to a low state as soon as I have to land on a generic airport of airfield...
So, obviously the need for immersion is quite different depending on the way of flying. For IFR, the landscape underneath becomes definitely less important than the detail level of the departing and landing airport. For low level VFR of course things are different. Nevertheless you will barely find your house, unless you have personally designed it as a 3D object in Bing maps. Generally the building details and sizes (as far as I can judge from my personal close environment) are not really on a useful level. There's a lot of space for improvement.
As I said at the beginning, this is only my personal judgement. Each Simmer may have a differnt look at things.... So, don't crucify me for not singing out all praises for MSFS ... at least not for the moment and not for the "F" part in it's name...