Due to the nature of AOS, it will last as long as it is profitable. Since it is a dinner show, a lively atmosphere is needed as part of the experience. They need to ensure it remains at near-full capacity for every show otherwise prices would go up and there would be less in attendance and therefore, less atmosphere, a critical part of the experience, which would reduce value for money. AOS seems to update the show every time attendance drops enough to be close to break-even and/or near it becoming noticeable that some seats aren't being filled (I have never seen AOS sadly - though I want to - so I'm not sure about the latter & the former is just a guess).
If projection mapping wasn't introduced, I'd say Heartland would have been it's last show before a major re-think.
To 'replace' it, they should just remove the word 'Outback' from the title of the attraction. So it is just the 'Australian Spectacular', which would allow them to also tell other Australian stories not related or linked to the outback. Retrospectively, they could rename the original show as just 'Outback'.
However, I'd say projection mapping has allowed Heartland to have a 3 year stay rather than a 1 year stay. As I will detail below though, projection mapping may only add a short-term boost to AOS though.
It should be noted AOS are heavily influenced by Olympic ceremonies. Ignatius Jones, who designed this segment in the Sydney 2000 Olympics Opening Ceremony, yes, you guessed it, helped design the original AOS. In 2002, he even directed and wrote a travelling musical theatre called The Man From Snowy River: Arena Spectacular (You can see the influence it had on AOS in the below video, which I think was filmed in Brisbane Entertainment Centre):
So no doubt, he was the man to help design AOS particularly since that film above was distributed by Village Roadshow. Back to the Sydney 2000 Olympics ceremonies though, those ceremonies heralded in the 'technology' era of Olympic ceremonies.
These types of ceremonies reached their peak a decade later with Beijing's massive effort in 2008. 2 years later, Vancouver did the 1st ever near-fully projection mapped ceremony, heralding in the 'projection mapping' era of Olympic ceremonies. Projection mapping was used prominently throughout that ceremony but this segment (from 01:35:55 to 01:41:44 - the impressive projection mapping really starts at 01:37:41) was what really heralded in that era as people then realised the possibilities projection mapping can provide. David Atkins creatively directed the Sydney & Vancouver Olympic ceremonies and helped Ignatius Jones with The Man From Snowy River: Arena Spectacular.
Projection mapping has been used prominently in all Olympic ceremonies since then except London 2012, who used it only in 1 segment. However, projection mapping has been critizied in Olympic ceremonies in the past 4 years as being 'lazy', 'cheap' and 'overused' as it has replaced many of the special effects once utilized in the Sydney 2000 to Beijing 2008 era. VRTP shouldn't fall into that trap as it will turn the show into a glorified cinema screen otherwise and regular visitors would easily see a lack of creativity in technology & special effects. Olympic ceremony directors have, since that criticism, in the past couple of years, began to try and blend projection mapping with technology more where budgets permit, which has reduced that criticism, though not fully. So it should be noted that how Olympic ceremonies evolve will likely be how AOS evolves.