h, when Praxis exploded the Klingons would be fubared. Without Earth there would be no Enterprise-D, then Soran would get in the Nexus and probably the Viridians would be fubared.
Actually without Kirk and Earth, the Viridians would have been perfectly fine.
The Enterprise-B would not have been in range to intercept the Nexus ribbon and save the El-Aurians.
Soran would not have been pulled from the Nexus and never blew up any star systems.