There are no such announced plans or projects for the Australian Army. I think one issue is that for Australia the Boxer is really a cavalry vehicle with a limited number of joint fires vehicles (maybe ambulances too). For Germany and Britain it is primarily an infantry carrier but with many specialised variants accompanying those carriers. For the sole Australian (planned) mechanised infantry battalion those troops will be carried in tracked IFVs (supported by tracked SPHs) so, if anything, an IFV mortar vehicle would make more sense.
Their approach also seems to be prioritizing strike at much longer range than afforded by mortars or howitzers.
As argued above, replacing 7 Bde’s artillery with SPHs made in Australia could make sense (rather than a new wheeled type whether that be a howitzer or a mortar).
Army has a motorised mortar capability, with the M125AS3 81mm mortar in-service with 3RAR (and until recently) 6RAR.
This however is due to exit service (along with the remainder of the M113AS4 fleet) in 2029 on current planning.
Despite this, Army retains a requirement for a mobile mortar capability. According to DTR Magazine (December 2024 edition), Army has been trialling the Scorpion self-propelled mortar system with a range of vehicles including the M113AS4 flat bed logistics vehicle, Hawkei and the 6x6 G Wagon. Army is also investigating integrating this system on a robotic unmanned ground vehicle, of unknown make.
Army needs a mobile fire support system that can operate regardless of season, weather or terrain that provide BLOS fires, area suppression, night fighting and obscurant effects. It also requires a fire support system that can be employed in littoral scenarios “straight off the boat” without any substantial set up time that both manpack mortars and towed artillery (of any kind) require.
There is no known formal project as yet to acquire a mobile mortar after LAND 400 Ph.3 had the mobile mortar capability axed on cost grounds, but the requirement is there and Army is actively assessing possible solutions.
Aside from it’s substantial rate of fire and reported speed in and out of action, the Scorpion mobile mortar system can be employed in mobile or fixed roles as required, is extremely quick in and out of action when mounted and has the capability to provide either 81mm or 120mm mortar fires via an integral quick change barrel system.
And depending on the vehicle it is fitted to, it can also meet that overwhelmingly important “PNG Highlands” requirement so popular hereabouts, being helicopter air-lift capable…