You were the first person in this thread to name "Rosetta" as a reason for continuing to use Snow Leopard, but apparently, you are not as well versed in Rosetta, and the PPC apps using it, as I thought:
1. You have no idea when Apple will cease selling SLS or return its price back to the original $499 retail price it sold for when Rosetta was eliminated from OS X Lion in 2011. It could come tomorrow, or as you suggest, in years to come.
2. Use of Snow Leopard Server in Virtualization, such as Parallels, is for one primary purpose: to regain access to Rosetta, so as to run PowerPC apps.
3. Snow Leopard Server is the only "off the shelf" means to regain access to Rosetta in a post-Snow Leopard world, such as Lion, Mt. Lion, Mavericks and Yosemite.
4. In "3 to 5 years down the road" Snow Leopard Server will run in virtualization, such as Parallels, exactly the same as it runs today! There is no "too far gone!"
5. Freehand MX has not been available for sale since Adobe acquired it, with the purpose of killing its competitive effect on Adobe's core products, back in 2005. Hence its only availability is to run existing copies of it in Snow Leopard with the Adobe supplied patch, available on its website. There are or will be no "latest Freehand on sale will be few versions away, far more advanced..."
6. So, when you suggest: "So if you're in the market for a new Mac, why not new software...? It defeats the purpose of getting a new Mac when the software is still relying on an ancient piece of architectural translation matrix bogged down by performance issue" you are missing the point of the analogy: There is NO new software available to replace Freehand MX and the only way to continue to utilize one's library of Freehand MX created graphic images is through the virtualization of SLS.
Also, on today's modern i5 and i7 Macs, Freehand MX runs faster in SLS in virtualization than it did on the old PPC iMac G4 and G5 for which it was developed.
Obsolescence is on the computer of the beholder: Better to pay $20 now for SLS and put it on the shelf, then to have to pay $100, $200, $499 or more later on!
Will it? Of course: Snow Leopard Server is the only means to regain access to Rosetta "off the shelf!" The demand is there, and once Apple raises its price, or eliminate sales altogether, 3rd party sources will take advantage of this lack of low-price competition to dramatically increase the price of their limited inventory.