i think A300 will only be released after A350 so as not to affect the sales of A200.
A200 is for those who want the cheapest DSLR and dun mind dun have a Live View.
A350 is for those who want a DSLR with a higher MP and want to have a Live View.
A300 is for those who want a DSLR and want to have a Live View.
Each of them is catered for different type of consumers and this way of marketing is very similar to what Sony has been doing for their compact digicams.
The above is based on what i had read on the Net over the past 2 weeks.