The proposal merges the two coins and they'll keep whatever stake they had, but in Darkcoin instead. It's the first "coin-merge" to ever happen in crypto.
I think it's a great idea !
Check the history of the British Aerospace industry. The country was chockfull of disparate plane makers all trying to solve the same problem. It was a no brainer to merge complimentary enterprises to work co-operatively on a more ambitious project.
I hereby nominate Darkcoin and Shadowcoin as "De-Havilland" and "Hawker Siddely" of crypto respectively,
who merged this...

with this....

to make this....

Maybe not the best analogy. The Concorde was retired because it was unprofitable. (jk)