OK, sounds like you might be serious.
I would say it would be possible but difficult. It would depend on a lot of things, age, your GA experience, your drive and lots of other stuff.
There are a lot of AG pilots getting older and within the next 10 years a lot of those will retire.
Fire work is there for a limited number on contract, call when needed work is patchy, some years you will do a lot others years none. Fire work is only for maybe 5 months maximum. AG work in Australia is a lot less than what it used to be, often in drier years there is no work at al for casual pilots which Is the majority.
Because of sparsity of work there is all sorts of competition for that work driving down wages and conditions. Even for 7 months work a year you will need to travel and be prepared to stay in some rough accomodation. It is possible to do a fire season in each hemisphere if all your planets align, that would be a liveable income but no family life. AG flying is not family friendly in these times, in days gone it was possible for a pilot to sleep in his own bed every night, I've known pilots who went through their entire career with one employer and based in one town. For all but a few those days are long gone. AG flying is a selfish job, if you absolutely love flying at it's basic best then it might be for you.