Regardless of the 'will fans travel to a GF' argument, it's honestly pretty poor that the location for the 2023 Grand Final is only being confirmed in late July. Also the fact it's a one year deal means it will be in a similar situation to this year unless the NRL wrap up next years (and possibly beyond) quickly.
If the GF was to move around, it would be best practice to have the location known by the start of the season. Hell, the Super Bowl locations are usually known a couple of years in advance.