Its not only a case of which airports will adequately handle an A320, but also which markets are able to be stimulated by the delivery of a genuine no-frills product - and which ports could support an 180 seat A320. I daresay a lot of the regional ports would be better served and their markets better stimulated if their flights have the ability to connect onwards with the same airline, or at least on a codeshare agreement of some form.
I am not in any way implying that I don't want Tiger to succeed, but it will be interesting to see how long a real no frills airline can survive on its own in Australia. DJ has evolved significantly since launch (not only due to the sad demise of Ansett) - the market shares DJ has on some sectors has risen and the mix of business/leisure travellers has changed to a lot more Suits coming onboard as a direct result of a lot of the changes that have been implemented as part of the New World Carrier strategy. Evolution has been a major key in DJ's success - it will be interesting to watch the effect Tiger has on the markets it enters.