Ginkgoopsida probably was not that diverse even in the past. It was very widely spread, but all finds are fairly similar to modern Ginkgo, so calling it diverse is stretching it. Then again it is possible we only can recognize relatives similar to modern Ginkgo.
In any case the main issue that without human intervention would have condemned Ginkgo to extinction is its inability to compete in new areas. Ginkgo are pretty robust and can survive the competition quite fine in areas they are established in, but more modern plants utterly crush it then it comes to spreading to new areas or adapting to changes in environment.
Faster sexual maturation and maybe a bird based method of spreading the seeds might help. But I do not think birds existed when Ginkgo evolved. So fundamentally it all comes down to faster rate of evolution. Ginkgo have sexual reproduction, so that is okay, but it simply would need to reproduce faster.
So faster rate of reproduction would be the answer to this question? While it strictly speaking tells what advantage over modern Ginkgo, not over modern angiosperms, the Ginkgo would need to have, the Ginkgo would have the huge advantage of a long headstart over angiosperms, so they probably would have managed, if they had been able to adapt as fast as angiosperms. It is not like Ginkgo are somehow otherwise inferior as plants.