As with all things in IT, it's possible. The sys admin job will now become service or cloud admin jobs. Help desk will become the cloud practitioner. The industry is changing, as it always has. Don't believe me, there are plent of people from the late 1990s and early 2000s who were huge Novell sys admins. The are still around today, because as the industry changed, they willing did so.
There will always be some companies that will have infrastructure on-premises, due to company rules or regulatory compliance. So Sys Admin for maintaining servers will be there but most will move towards managing those servers in data centers. Help Desk will be valuable to help with hardware and support for applications and end-user security.
The irony behind this to business is that most employees will never know that your job as Sys Admin that your now managing the Cloud Infrastructure instead of on-premises servers. If you're Help Desk, most will still have a problem connecting to their WVD or VDI, Wireless may still be an issue, printers will still need troubleshooting. Sharepoint sites will still be navigation hell. People will still need help with Microsoft Teams and setting 2FA, webcams, Updates to on-premises workstations may still break. RAM can flake out or power supplies die. Printers not connecting on the network.
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