...but to my way of thinking if the industry is to survive then newby's have to come along and be trained and operators will have to take a chance on them at some stage...
That's not the trend, nor has it been for many years. One AT-802 can do the work of five or six smaller ag airplanes. One isn't going to find an operator who's going to take a chance on a "newby" in an 802 in order to benifit the industry. It's a business, and unlike the airlines, most operators don't train you. They're looking for experienced pilots.
In the past, pilots would gain experience by gradually working their way into a Pawnee, Ag Truck, or AgCat. Today many those aircraft simply no longer fly, or have been relegated to banner towing or glider towing, and the work is taken up by turbine airplanes that fly faster, haul more, and require substantially more pilot experience for insurance purposes. One airplane doing the work of several means that one pilot is employed instead of several...the trend has been for less and less pilots in demand. The average age of ag pilots has traditionally been higher than other segments of the industry such as the airlines.
An operator who will "take a chance" isn't just taking a chance on your ability to not kill yourself at low level. The flying is the easy part, and it's a small part of being an ag pilot. Inherent to that flying however is the way it's done. It's not merely a matter of flying low and not hurting yourself. That part is a given. The part that's critical is exact spacing of swath runs, exact altitude, proper calibration and coverage, drift, etc. Crop inspection, chemical mixing, and numerous other aspects of the business. An operator who takes a chance is taking a chance that you won't leave skips in the field, cause damage to other susceptible crops with drift, spray the wrong field, etc. With chemicals that can cost hundreds of dollars a gallon or litre, a single mistake can cost the profits of an entire season, and even put an operator out of business. Drift claims can ruin an operator, bring expensive law suits, and cost the reputation and livlihood of the operator or his associates.
Unlike a Cessna 172 or a Katana, an airplane such as an AT-502 is unstable, and can be a handful in turbulence. The center of gravity is constantly changing, as are the flight characteristics. The turbine engine alone costs five or ten times what the light airplane you train in does, and that can all be destroyed by a hot start before you ever start to taxi. Power response isn't instant when you need it, and you have to think and fly well ahead of the airplane. Flying is precise, to much tighter tolerances than instrument flight (such as an ILS), without the obstacle clearance protections of an instrument approach.
Yes, you can learn to do it. Yes, you can find work. Be aware it can be very difficult, and even when you find it, you may end up working minimum wage mixing chemicals and fixing tractors and pumps for several years before you're actually allowed to fly...depending on the operator. Then again, you may find an operator who can put you to work.
Most ag pilots have mechanical aptitude, many are certificated mechanics...an important skill when it comes to doing this sort of work. It is especially important because sometimes no one is there to help you or fix your equipment; it may very well be up to you. Be aware that there's a lot more to being a mechanic than to being a pilot...which vastly expands what you need to know to do the job properly.
Again, I don't intend to discourage you, but to possibly give you a clearer picture of the realities of the business. It's a tough business, a shrinking industry, and as said before, a very tough nut to crack.