I agree that the contract will not go for as high a price, but again, remember, you have to keep in mind cost of living changes and inflation. The earliest any contract will have 10 years left on is 2032. $17,000 in 2032 dollars, if inflation continues at historical averages, is potentially equal to $7200 on 2007 dollars.
Some may not consider that a great deal, but let's assume it's a 160 point contract, which puts the annual 2007 maintenance cost around $700. This would give the person access to 160 points per year at roughly $8.75 per point, still below what points are currently renting at today. Their potential cost savings at this rate versus simply renting points is around $2000 over 10 years if they would have maintained the same vacation habits. Even today, this scenario could prove attractive to some people.
Your second point is much more poignant. If Disney waives ROFR, there would certainly be downward pressure on sellers and price could drop, even after adjusted for inflation.
But at the same time, if Disney choses to offer assement extensions on other resorts, even if the current owner doesen't buy in, it would extend the life and prolong the value of the resort, as a buyer in a resale situation could potentially purchase the extended access.
In the end, nobody will know until it happens. My personal belief is that the contracts will hold absolute value in relation to purchasing power well into their 'sunset years', and barring some unforseen deflationary pressure, the purchasing power of a dollar will continue to decrease.
Cheers