I don't expect much growth in price and adoption for this coin but they've some a long way from being just a meme coin. I'm surprised that they're still around to be honest and kudos to them for outlasting many other early cryptos. I guess many people still finds value in them like the faster confirmation and cheaper transaction fees compared to bitcoin as you mentioned.
It's because of the community always building the hype of this coin and it still survive until now even the coin itself is doesn't have anything special compared to other coins. I think many crypto people love dogs so they use dogecoin for like tipping purpose or just for collecting. I'm sure the growth of this coin won't big and just like you said it's just meme coin. But if the community build the hype and the whales are supporting this coin this coin's price could be booming even it's a just so so coin
There's no more hype is this coin, I mean they have been in the market, withstand their initial released and as the OP have said, they used to be the "Meme coin" here. They have grown so much already, crypto enthusiast knows what this coin is and now taking advantage of it. Dogecoin might not be big, but they will definitely stay in the market thru ups and down and will still have a purpose as compare to the almost 2000 altcoins that we have.