Nothing stops Canada from severing those ties completely by the way, if they wanted to they could do this easily, and the same goes for Australia and NZ.
Give it a couple of years as we've got another one in the pipeline and we don't put them too close together.
But tacitly admitting a poor cost/benefit with a reductio ad absurdum argument is not a great start anyway, because the actual situation is not an absurd one and margins matter.
Stripping most of that funding from the useless crown representative and entourage would be a great idea. Could be done tomorrow with acts of parliament and executive with no fanfare and no need for constitutional grandstanding. The fact they don't gives the imagination a good starting point for how much it would cost to be a republic.