Since upgrades cannot be confirmed, then at the moment there are no seats for upgrade at this time. If you are interested in upgrading, then you might as well register since you have nothing to lose. There are currently 1st class seats available for sale so its not sold out yet and theres a chance
And remember that the chance of a successful upgrade waitlist clearing is dependent on two factors, being the QF FF status of the account from which the points or upgrade credits will be sourced, and then based on the date/time at which you joined the waitlist.
There is no cost to waitlist, and you can cancel your waitlist request up until the time the waitlist has been confirmed with no penalty.