If you aren't familiar with Birthright, and wouldn't be interested in a 5E update . . . that's cool. If you ARE familiar with Birthright and aren't interested . . . that's cool.
But there are a lot of folks in this thread nerdsplaining how a 5E Birthright is just unnecessary . . . based on zero knowledge of the setting.
The setting itself was somewhat generic fantasy, if well done and much more cohesive than the Realms, Greyhawk, or Mystara. But very flavorful with the adjustments of boss monsters (ansheigh and ersheigh). Halflings had an interesting twist with a connection to the shadow plane, elves had an interested twist in being genocidal human-hating folks (with epithets like "man-slayer" tossed around).
But what really set Birthright apart was it's "hook" back in the 2E days, the rulership layer. Today's games have it beat at that schtick, but at the time it was very different.
A revived Birthright without the rulership game would probably not be a big seller for WotC . . . but fans would certainly appreciate the update, especially opening up the setting on the DM's Guild. But a revival WITH a well-designed rulership layer . . . . now that would be awesome!!! I'd buy that for a dollar!
Are there problems with the setting that would need revising? The close cultural pastiches would have to be handled very carefully. The "always evil" goblins and orogs would need revision. I don't see a problem with the literal divine birthright to rulership aspect, or the multiple religious sects per diety aspect either. The religions of the setting have to be carefully reviewed in the same way the cultures do, to make sure the game isn't carrying over real-world stereotypes into Cerilia . . .
It would be a lot of work to do it right . . . . would the return on investment make it worthwhile? It's probably a better bet to just open the setting on the DM's Guild and let some passionate fans take a crack at it . . . .
But if WotC does give it a shot . . . . I'm game!