Limits on the number of domain names that can be owned is unworkable. It would just result in multiple holding entities and achieve nothing.
If domain portfolio owners want to increase the value of their portfolio, there is only one generic reliable way to do that - grow the market. So what does that mean?
There are two parts to growing a market - growing supply and growing demand. to ensure portfolio values increase, you have to grow both parts in some sort of balance. Supply is growing systematically - IOW, every day, more and more .au names expire, get registered and are available for trading. So how do we grow demand?
Growing demand means more buyers paying higher prices. And this is the real issue, because for many domainers buying expired and aftermarket names, more buyers is more competition and more cost in growing a portfolio. but that mindset needs to change, because that is exactly what will enhance the value of every portfolio. it is in every domainer or portfolio owners interest to spread the word as widely as possible, to get as many people interested in the domain trading as possible, because that will push prices up towards their inherent value quicker and thereby increase your portfolio value quickest. it seems counter-intuitive, because we all want to buy low and sell high, but when you think about it, to sell high you need high prices, and we're all in this particular market early, so like all early stage markets we carry the higher risk, but can expect the higher reward.
So if you want your domain portfolio to increase rapidly in value, tell everyone you can to get involved in domain trading.