It's unlikely the 65" OLED will sell for the price of the Plasma as it's been predicted by the industry experts that OLED will run 1.5-2 times the price of 4K UHD LCD through 2015.
The serious production run for global distribution starts in December at LG's M2 plant and LG has three manufacturers in China that will be buying to rebadge and Panasonic, Sony may also and since they have no real OLED competition they rule the supply/demand factors and Pricing.
I would guess we may never see the 65" drop below other flagships like the Sony X950B, Panny AX900, Samsung HU9000 as they have no reason to presently anyways. The only time see these bad boys get down to the price of the plasma is when they are doing model year changeover to clear them out.
If your not in NEED of a TV and uncertain you may want to wait until CES as Samsung, LG and others likely will have new efforts at Q-Dot Tech and further expansion of 4K production/sourcing partnerships likely will be announced in early Jan 2015.
Personally, I've had negative experiences with Plasma ownership because I've had bright sunny rooms which destroy even the best plasma but that Samsung is the closest to looking like an LCD.
You just need to audition 4K and determine if it's for you or how often you want to buy a new TV if you decide to postpone that leap. Believe me most everyone would love to get a 65" OLED at the price of a Tech that's received it's death sentence - OLED is in it's infancy and plasma is at the end of the road so pricing impacts those scenario's accordingly at opposite ends, but if your a plasma fan and have light controlled viewing then go for it as that opportunity will be gone soon. Good Luck!