5.2 -> 5.3 without single mode?

[Stephen Montgomery-Smith]

M. Warner Losh wrote:
> In message: <E1CXK4m-0006Je-00._pppp-mail-ru at f21.mail.ru>
>             dima <_pppp at mail.ru> writes:
> : > Is it possible to cvsup from 5.2 to 5.3 without booting in single mode?
> : > I have a remote machine and want update it, but it is no console access,
> : > only SSH.
> : You don't actually need to reboot in single-user mode. Just make sure your users wouldn't use the server hard during the
> : # mergemaster -p
> : # make installworld
> : # mergemaster
> : cycle. You can basically disable all the services but sshd for that task & enable them again after the second reboot.
> 
> While you don't NEED to go into single user (I do the above all the
> time), you are setting yourself up to get screwed the first time that
> a new, common system call is introudced...
> 

So if there is a new common system call introduced, will it arrive with 
a nice entry in UPDATING plus a HEADS UP?

Stephen