I was actually thinking eth or decred would be ones to go for for this but especially eth once it gets the upgrade in November.
I haven't looked into cardano much tbh but I remember it's been around for a while so it's possible they'll pick that one.
I thought it was funny Solana replied to his tweet though

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Yep, I doubled down on Ethereum earlier this year as I had a feeling there was going to be a shift in sentiment.
To tell the truth, I'm just a lazy speculator and I just buy 20 quids worths of every new token on Coinbase for luck.
I'm just rifling through them now learning about them and trying to gauge which ones Musk could tout next

I think the old adage "buy the rumour and sell the news" works well in these wild west days of crypto.