Also note that from April 2, we will be ending supported for all non-secure domains – this includes SC, SCA but also Site Builder, Redirect URLs, Promotional URLs, Email Campaigns, etc. All domains will need to be secured with a certificate/HTTPS

@Steve Goldberg what happens to old test/demo accounts that do not have any provisioned Secure Customer Domains? I have a couple old test (tstdrvXXXX) NetSuite accounts that I use for test/demo purposes. Will these accounts no longer be useable?

The accounts will probably be fine, but none of the sites will work, no. If you still have a legitimate claim to those test drive accounts, you'll need to talk to your account manager about provisioning some secure domain slots to them.

And what happend to customer accounts, we normally have staging domains or similar, they will need to ask for more slots to account managers ?

Yes, they will need to purchase additional ones