With all the Rebirth stuff going on and me just liking history just 'cause I wonder if looking back at all Crisis events and New Universes could you consider any major shift in the Universe/Multiverse a Flashpoint event by warping Space-Time to bring about a New Universe. Here is a list I compiled starting with the birth of the DC Universe

Flashpoints
1) End of the 2nd World Gods and birth of the 3rd World Gods - Brought about by a great War that resulted in the destruction of Krypton & release of a Exotic Form of Matter that would later become known as the Speed Force. Jay Garrick is the first to harness this power while other forms of "super" science are derived from the birth of this Multiverse. This Multiverse ran from 1,938 to 1,952 Our Time with the most well known Universes that of Superman, Batman, Wonder Woman, Justice Society etc. Early on these were all completely seperate Worlds with their own version of Atlantis, 1,940's, and Future before Merging with the first actual meeting between Superman and Batman when they boarded the Varania Ship.

2) War of the 3rd World - Running from 1,952 to 1,970 - This early Silver Age period had some of the wildest stories due to the effects of a Cosmic war with multiple Alien invasions caused by civilization attempting to avert the immense destruction as a result from this unseen war. The Flash Barry Allen is integral in saving billions of people including the lost JSA and to better survive this war Annual meetings between Worlds are held to take on the greatest threats.

3) Birth of the 4th World - Running from 1,970 to 1,986 - This was the most Stable time of the early Multiverse with Batman & Robin fully getting Back to basics, The JLA hitting their Prime etc. Annual meetings between Worlds are still held to keep out major threats. The biggest thing threat to this Multiverse is the Anti-Monitor who has been destroying Universes since the Inception of the 4th World to build up his strength until 15 y/rs later he is ready.

4) The New Earth Era - Running from 1,986 to 2011 - The most well known Universe, however much Darker with multiple heroes suffering unspeakable maiming, Death is toyed with too much which results in the Blackest Knight.

5) The 5th World/Rebirth - This was intended to be the Birth of the 5th world but with the Final Crisis & merging of the Wildstorm and other universes but 10 yrs of Life Experiences were stolen making less capable heroes however shades of the "Fifth World" still leak through which allow just the 7 Justice League members to take on Darkseid on multiple occasion without this causing the same amount of destruction as Final Crisis