ECW was so great it needed two promotions to fill the void it left. Ring of Honor is the successor to the technical wrestling and Combat Zone Wrestling is the successor to hardcore wrestling. Both promotions run most of their shows in ECW's home venues such as The Arena in Philadelphia and The Manhattan Center in New York. However, they didn't belong to the NWA and out of these two, only ROH has a television deal.
The UFC is considered by most to be the successor to Pro Wrestling in general, since it follows the same exact model, although lately they have been trying to move away from that structure.
Tongue in cheek all women's promotion GLOW spawned a number of spiritual successors, such as POWW, the LPWA, CRUSH, Women Of Wrestling and Wrestlicious. Despite their names and premises, SHIMMER and SHINE are not examples, instead being recurring showcases of the best and the future of the business. Even the names are slightly coincidental, GLOW being an acronym, the latter two being SWA and SW. Since SHINE has partnered with Big Vito's school though, both it and ROH Academy sharing SHIMMER, could conceivably become spiritual successors to GLOW in the sense that they could put a bunch of rookies on television.
A humorous case happened in the 2000s to early 2010s when the NWA launched a revival of Championship Wrestling from Florida and The WWE launched a revival of Florida Championship Wrestling. For those who don't get it, they both ran revivals of the same company at once. CWF had been erroneously called FCW for years and was forced to temporarily change its name to FCW for a time in the nineties.