Let alone meme coins like Dogecoin becoming new BTC, even ETH which is the best altcoin is unlikely to become new BTC. In fact, there have been lots of new projects created to replace BTC, but all of them ended up failing. Because Bitcoin is too strong to beat, so Bitcoin is like a mother to other cryptocurrencies. No matter how big Elon Musk's influence is, it's impossible for Dogecoin to overtake Bitcoin, even I'm not sure Elon Musk is able to return Dogecoin to ATH prices.
There is only one btc, that is why it cant be replaced anymore. Any coins next to btc are only just an altcoin and only the altcoins have the permission to compete with each other. If there are projects with a vision to replace btc, that owner must be out of his mind. He don't have a respect to the one that started it all and I am sure that investors will avoid his project in an instant after knowing his intention.
It will be hard for elon to hype doge again to its ath because he already lose a lot of followers but it wasn't the dogecoin that lost the trust of the investors but it was Elon because they know that Elon is only using the coin for his own good.