I've flown IL-2 Sturmovik: 1946 on/off for around 6 years now, and I think you'd mostly wrong if you were talking about proper flight simulators. As it is, this is being done by Gaijin, which means they will probably not be pushing the limits of realism like IL-2 Sturmovik: Cliffs of Dover has been doing. Either way, let me tackle your points one by one!
I'm not terribly interested in flight games. When you arent actually on the ground, maps are nothing but different backgrounds to fly over. I also feel like tactics get thrown out of the window when you're in a giant open space like the air.
- Engagements should indeed happen further up, but if a dogfight continues for long enough, it will go all the way down to the terrain. I have seen people make excellent use of terrain for evasive manoeuvres, including evasive stunts that cause less experienced pilots to crash into the ground trying to follow.
- If you don't have a minimap that shows where you and your opponents are (i.e. realistic), the terrain is what you use to navigate with relation to an "actual map". This is much trickier than you'd think with big maps dozens of square km/miles. If you also consider weather and the sun's position to be part of the map, they have a totally non-trivial impact on combat. Ducking into clouds for cover and using the sun behind your back are both very sound tactical choices. Maps of the Pacific are harder in that sometimes you'll fly a long time without a whiff of land... but you have carrier navigational aids such as beacons etc.
- Regarding tactics, I've already mentioned ducking into clouds and being up-sun. Other than that, entire books have been dedicated to the subject of air combat (including "In Pursuit", which you should be able to get the pdf of). On a more practical level, you have E, or Energy, which stands for altitude+speed. You can convert E into speed or altitude, and gives you an idea of how "prepared" you are for combat. Estimating your enemy's E is integral to air combat. See also my other comments below.
The reason why I don't see any selling point in World of Warplanes is because unlike tanks in World of Tanks, planes are very fragile. In World of Tanks, your facing matters, hulling-down matters, using terrain as cover matters because every tank is unique. In World of Warplanes, it's just open space and planes are just shooting at each others. Unless they make each plane behaves differently, they are just the beautifully modelled hitboxes of varying sizes.
The only appeal is its accesability to those who are looking for more simple arcade games. Just my two cents, though.
- Have you tried to shoot down a TBF Avenger with an early-variant zero? There's a reason Grumman was called "Grumman Ironworks"
- Some planes are fragile, some aren't, and some withstand +20mm cannon punishment and others don't. Every plane is unique. Furthermore, facing is very important. Trying to take down a plane from dead 6 gives you a minimal target to shoot at. Depending on the damage modelling in the game, hitting from dead six, besides being harder, will also cause lower damage since the enemy plane is not pulling any G's (which can cause cannon shots to snap off a wing more often than not...) and since the shape of the airplane means the bullet might get slightly deflected. Plus, the pilot usually has armour plane behind him, depending on the plane. If you do deflection shooting, estimating deflection is always a challenge. Plus, you can expose interesting targets, such as hitting the canopy (instead of armour plate) and trying to get the pilot, the belly of the airplane (there's usually some fuel tanks there), the engine, or fuel tanks at or near the wing roots.
- Aside from all this, planes have immensely different flying characteristics. Turn rate, roll rate, climb rate and acceleration are all parametrised by current altitude and speed. Of course there is also max speed. You need to know how your plane behaves in relation to the enemy you are facing (which you also have to identify. This can be surprisingly hard at speeds of 300mph). For instance, the F4F Wildcat was outclassed in mostly all respects (except capability to sustain damage) by the A6M Zero. However, it was found out that in high speed dives, the Zero lost left (or right, I forget which) aileron authority. This meant that a turning dive was pretty much the only way to get away from the Zero.
I'm gonna stop with the wall of text now, but just bring up a couple points. There is an absolutely insane amount of tactics involved in air combat as long as airplanes aren't modelled all equally. I never realised it until I flew in a online in a full-real server. No matter what you do or what planes you're flying, those guys will get behind you and shoot you down - heck, our own Erkki does that all the time. He'd probably have a lot more to say about this, and a lot better too. The deeper you go, the more there is.
The question is how all this stuff is going to be modelled in War Thunder. Gaijin came out with Wings of Prey, which had actually simplified IL2's flight and damage modelling. I'm not sure they're gonna go the other way with this one, which really is too bad for those of us who are into hard core realism, but there you go. If damage and flight modelling aren't done properly, this won't have nearly as many tactics as in "the real thing", as you guys have said.