A buyer who is prepared to pay $ 30,000 for a domain name for their own use for whatever reason they have, should be happy to pay $200 a month if that is the only way they can access the domain and use it. If it's a business that believes they can gain SEO or type in traffic to value it at $30k but its not for sale, only for lease, they will lease it if the leasing conditions are sufficient. The economics are exactly the same as applies to lease vs. buy cars, commercial property, etc. Cash flow, capex, tax, risk etc.
It is very different to leasing a car or renting property because with a domain the business is generally based on it.
For the type buyer who is willing to pay $30,000 to buy the domain I think a very small % would see leasing for $200/mo as a good option. Domainers have been trying this for a long time in the .com space (and the attraction for domainers is obvious) but domain leasing has never really caught on. The issue is that anything that is done with the domain is not owned by the person leasing the name.
If you want a property comparison I'd compare it to renting a block of land then deciding to build a house on that land you don't own.
If it is leased for type in traffic that is different, but the average 30k .com.au won't produce any real ROI from type in traffic in my view. SEO, the question again is will people bother for a name they don't own, some might, but I think it is limited.
In the end, it is a matter of demand. If you have a name that someone else wants to use, and the only way they can use it is to lease it, then leasing becomes a market in its own right - just as property rentals are. It may not be accepted practice now, but that doesn't mean it never will be.
So if there was a house for sale that you really liked but the owner wouldn't sell, would you say "ok can I rent it?".
I think most people would just buy something else. electricity.com.au -> power.com.au -> utilities.com.au......There is always reasonable alternatives.
The higher the purchase price, the more attractive leasing becomes.
In my view the higher the price, the more likely they will buy something else.
A lessee may have an option to buy and a right to terminate the lease under certain conditions (say by buying out a portion of the remaining value of the lease agreement). There are many ways to structure such a thing, but leasing is a very well accepted financial structure that exists in all sorts of asset markets for very good reasons.
They'll want that option most of the time, but the average domainer sees the attraction of leasing in terms of not having to sell.
I'm not saying that leasing is a floodgate waiting to rain cash on you, just that it is a policy change that will help smart entrepreneurs develop new models to make money from domains - and that stimulates demand.
Well you said,
"I believe domain leasing is the single policy issue that has the greatest potential to increase the value of a domain portfolio."
I don't agree with that at all. In my view the policy change that would have the greatest effect on prices would be to take off all the ownership restrictions and forget about formulating ideas on how people should/shouldn't be able to use a name which creates uncertainty for domain owners.