3.2 is around the corner and these achievements will be no longer attainable after that.
If you are a few emblems away from the next target, then you may consider get them soon.
After that, we will see Dungeon & Raid Emblems and highest emblems achievement is 2500 Dungeon & Raid Emblems.
Reference: 3.2 PTR Patch Notes
- The existing achievements to collect 1, 25, 50, etc. Emblems of Heroism, Valor, and Conquest have been converted to Feats of Strength since Heroism and Valor Emblems are no longer attainable.
- New achievements have been added to collect various amounts of any combination of emblems.