Maybe, but there's no way to know, because see above. It would be interesting to see the ratings of network shows that were renewed 1987-1991, that might give a better idea of whether TNG would have made the cut in its early seasons.
I'm not sure ratings would tell the complete story.
Would TNG draw as many viewers if it had to compete directly with Monday Night Football or the Cosby Show? What if it had ended up on Fox which had limited penetration during its early years? Would it have even been the same show had it aired on a network?
Was TNG popular and successful? Of course. But you simply can't look at that popularity and success in a vacuum. Would we still be talking about it today if it had been called Space Patrol
? Would it have gotten the huge budget right out of the gate if it wasn't trading on the success of the Star Trek
name? Would it have gotten prime time slots if it hadn't been associated with Star Trek
? Would the general public have been eager to watch it if it hadn't been associated with Star Trek
? I think the answer to all those questions is 'no'.