No idea. I think Brazil would have won the World Cup if Ronaldo was 100% fit for the final, with or without Romario. Ronaldo was clearly the best player in the tournament and the whole mysterious hospital story in the night before the final with Ronaldo then clearly not fit at all disrupted the team. Maybe with Romario available they would have left Ronaldo out of the starting XI in the final and trusted him to finish the job? It's all speculation though. I just disagree strongly with your comment that Romario wasn't anywhere near the player he was 4 years before. He was in brilliant form up to the World Cup.
That might've been a bit over-the-top to say, but I find it tough to call it a big feck up by Zagallo since Brazil made it to the final, and didn't look like missing Romario at any stage, also because Bebeto turned up and they had a Rivaldo about to peak, and a Ronaldo peaking.