How far has speaker technology come?

Currently I am using my dad's old Wharfedale E-90s. From what I get from talking to him about it, they retailed for somewhere in the neighborhood of $2000 dollars back in the 80's when he bought them. I guess if you want to scale the price back then to todays money, taking into account inflation and what not, they are probably the equivalent of an $8000 pair of speakers in todays market, at least as far as dollar value is concerned. But anyways, does anyone have any idea or opinion as to what I improvements I should expect to hear if I were to buy a more "modern" speaker which retailed for about $8000 new? Could I expect the quality to be substantially better, seeing how these speakers are over 20yrs old? Can a dollar today buy more speaker "bang" for the buck, or has it stayed the same over the past 2 decades? Has the area truly advanced, or is it just running around in circles? Is the progression as obvious as digital technology? My dad is also looking to purchase a newer speaker for about $2000 used. For that amount of money, could he expect to find a speaker "better" than the E-90s? I've asked retailers in my area, but their opinions are inherently biased, so I want a "real" opinion. I do understand that the word "better" is subjective to interpretation, but I am sure there has to be some widely acceptable basis for evaluation. Clarity, imaging, detail, presentation.... all those good things.

Thanks in advance