You're right, although i don't think it'll be obsolete that soon when bluray is still somewhat popular.
These mediums of storage still have their uses, of course, but they aren't as important as they once were. 10 or 15 years ago, people probably thought it would be impossible to have some cheap type of cloud storage. Now, you get 15GB for free on Google Drive with every account you create, and that's just one provider. We can have negative opinions about anything Google is doing, but it's still a fact. Internet speeds are getting faster and faster, making it easier to upload and download from clouds, and that's what most people prefer.
Yes, that's true, but at any time Google and other cloud storage companies could change their mind and offer less GB space, but I think that's unlikely at least for now., I've used the drive a lot as a backup for encrypted data.
Physical backups in steel will always be better due to their durability and resistance against the elements of nature, but I'd not exclude digital backups from my list, as you can encrypt them and be easier to access physically, which we cannot. depending on is just one form of backup.
Tips for exporting encrypted backups from a standard BIP39 or Electrum wallet here.As for the OP, I found the question a bit vague, storing crypto on pen drives has always been possible, before BIP39 and to this day in some wallets such as bitcoin core, the form of backup is through keystore files encrypted with a password, this file contains the keys, descriptors to move the funds. There are thousands of ways to store this safely on digital media.
Now if the OP's question is to run full nodes on pen drives, although it has 2tb pen drives, it'd be more worthwhile to use an SSD, they are not as durable as an HDD, but they are more resistant than them as they do not have mechanical parts.