These are all good points, but I would like to ask how you would propose this be done? Green energy costs more than coal. The way around this is to price coal emissions - because they do come at a price, a very high cost of dealing with a deteriorating climate.
Whether you price emissions through a market ETS or force industry to use green energy, it will not be as cheap as coal, so the end effect is the same as it is now.
How exactly would you suggest we circumvent this?
Fundamentally it is about productivity of energy supply and, since virtually all activity uses energy, productivity of the overall economy.
Fossil fuels (and nuclear, hydro etc) are essentially a means of leverage. Man puts x amount of effort in to extract the energy, and we get vastly more back than we put in.
An easy way to demonstrate this was the old exercise bike and treadmill that the Hydro (Tas) used to have as part of public education exhibits etc. If you pedal as hard as you can possibly manage then with a bit of luck you'll generate all of 200 Watts and it's much the same running on the treadmill. And of course you will quickly become exhausted doing this.
Now, you'd need to sprint for a good 10 hours to heat the water for a hot shower. And you'd need to sprint for 15 hours non-stop to generate the equivalent power we get from just one litre of diesel.
So fossil fuels are a means of leverage. We put very little in, in order to get a lot out. Hence the vast majority are not employed in any form of energy extraction industry and man is able to do things (eg flight) that could not possibly be powered by muscles.
The problem with "more expensive" sources is that fundamentally, they are "less productive". We have to put more effort in per unit of energy produced. Now think about that... If we are going to put a lot more in so as to get the same out, then all of a sudden we're going to have an awful lot of people employed in the electricity generation industry and that is why it becomes expensive.
It's like any industry. If you switch to less productive means of doing things then you need to either employ more people to do the same work, or you do less work with the same people, or you do some combination of the above.
If we take it as given that coal is generally the cheapest (most productive) means of generating electricity in Australia, then any decision to cease using it is basically a decision to drop the overall productivity of the economy. Given that we don't have unlimited labour resources to offset the productivity drop, that ultimately means we end up with less overall economic wealth than we would otherwise have.
Technically, yes we could switch to a predominantly renewable energy supply in SE Australia (Qld, NSW, ACT, Vic, Tas, SA) I have little doubt about that. But the problem being faced nationally is probably best explained by these figures from Tas (where this energy debate is decades old...).
Electrolytic smelting = 45%
Paper manufacturing = 7%
Other heavy industry = 8%
Space heating = 12%
Water heating = 8%
General use electricity (light industrial, commercial and residential) = 20%
Of all of that, only the last 20% is a reasonably "safe" electrical load. The 60% consumed by heavy industry exists in Tas only due to electricity being at a competitive price. And the 20% used for water or space heating is an electrical load only whilst electricity remains competitive with other fuels (noting that historically electricity had very little of the space heating market).
If a new power source can not supply electricity at a price that is viable for smelting then there is simply no point in building it. If we can't expand or maintain supply at that price, then the smelters will ultimately be out of business. Now, those smelters and mills just happen to account for well over half the state's exports...
The situation isn't as severe nationally but the same principle applies. There is simply no point in building any new source of supply with a production cost above the lowest value use of electricity - market supply and demand 101 there.