Congrats to DOGE for breaking the mold and blazing new trails: So far, I read the OP and it's a surprise they can even consider this.
Are there any other coins that completely changed their basic nature, at least among the top 10?
I didn't think this was "allowed", but DOGE might go where no coin has gone before.
Indeed, none in the top 10 have done that! I'm under the impression that Dogecoin's community is more flexible than the others, and the loyal miners wouldn't mind taking a small cut by implementing PoS if it means a more secure future for the coin in the long run (which is not the case in BTC's community, where more than a third of the miners continue to mine at ghash.io)
And it's nice to see that the coin is backed not only by a plethora of awesome users, but also by many intelligent devs and leaders.
However, the case for PoS is a really though call, considering that a few big holders will get most of the new coins. But then again, there won't be that many new coins, and inflation could change to 2.5% instead of 5. Or perhaps the value relative to LTC would go up enough for PoW to remain secure. However, does PoW truly offer a better distribution, considering the huge ASIC farms?
I guess only the future will tell