There is no Su-37 left in the World. It's gone, please make a note of it and if you could - do not refer to it again as to the live or production aircraft.

There is no stealth - have been proven many times over and over. All US bombers (F-117, B-2 and I am sure the future ones) are clearly visible to Russian and Czechoslovakian (Tesla) made radars.

Sukhoi fighters could employ stealth by stopping in the air - that's just as far as stealth goes.

Su-27 and MiG-29 families aircraft outmaneuvers any modern US aircraft at least three times. If you'd like to say there will be no dog-fight in the future - I hope not but we'll have to to see.

Sukhoi fighters successfully penetrated Kitty-Hawk's defense, won the Indian training (9:1) and God knows what else they could do.

After tests were conducted engines without thrust vectoring were installed and the whole airframe was tested again.

Then results were compared and the difference was studied. Result was: thrust vectoring did have positive results but maintenance was overwhelming and it was decided not to use it in production models.

I think in future there will be no more any aircraft without TVC

F-22 has 2D TVC. On F-15 had been tested TVC but americans are behind russians in this aspect (and in many other 8-) ).
Maybe TVC is now to expensive but without.

Why thrust vectoring was ruled as not cost effective on Su-37?

We have to look at the design features of Su-27 family aircraft. Basically they all have one shared feature - they all aft CG aircraft which makes any plane unstable.
Sukhoi bureau made the aircraft controlled by fly-by-wire where computers hold all surfaces in-check. That's another reason control surfaces has to be big enough so they could have more power than rear CG moments. The whole aerodynamical focus of the aircraft moved aft.

Now, when pilot needs to do the a vertical maneuver (in aircraft axis) - controls are slightly moved in that direction and then all controls are holding aircraft in opposite direction to compensate the moments created by the aft focus.
In fact controls fighting the aircraft from going further of initial direction. That's the secret of super maneuverability here. And that's the reason thrust-vectoring didn't produce much of a difference on Su-37.
Look at the pictures of Su-27 family aircraft in the air. Doesn't controls look odd? Aircraft on high angles of attack while all controls dictating that aircraft is in normal or negative angles.
Look at F-16 or F-18 pulling from the loop and Su-35 coming out of the same thing! See the difference?