The End Of Big Iron?

I would assume that demand has been off for such high wattage stuff. Due to the economy? Saturation? Dunno.

Practically speaking, the big power was really only useful for bass content in big inefficient woofers.

Nowadays, many speaker manufacturers have moved away from very inefficient acoustic suspension designs and are using more efficient bass reflex variants and even some really efficient horn-loaded configurations.

In addition, many audiophiles are opting for separate powered-subwoofers, taking a load off the "full range" speakers and therefore also their amplifiers.

Personally, I would be intrigued by a really big acoustic suspension woofer powered by some gazonga amp -- back to the old days. (But isn't this just what a lot of subwoofers are?)

"Nowadays, many speaker manufacturers have moved away from very inefficient acoustic suspension designs and are using more efficient bass reflex variants and even some really efficient horn-loaded configurations."

Maybe, but most "quality" speakers you see these days are small to fit mot peoples lifestyles better and go for an extended low end to boot, which means they are inherently inefficient and benefit from watts and current.

Flip side is many with these speakers don't realize the shortcomings they may be living with in lieu of 250w/ch or more often needed to realize full potential and/or they don't care all that much even if they do.

The difference in attainable SPLs from a 1,000 watt amp and a 600 watt amp is just over 2dB. It's not a big deal.

Onhwy61 maybe it's not big deal on 1kHz, but bigger on other frequencies depending on speaker. If you plan to install Meyer Sound arrays in your listening room, than probably you'll feel difference.
For average home rooms and speakers It's not big deal anyways.

I think that megawatt power amps were necessary if you could afford them + you had a big enough room for them to perform to their max to create outdoor concert-level SPLs.

I seem to also think that megawatt power amps are dwindling due to the economy. These amps require huge power transformers & just the weight of these power xformers necessitates the use of thick metal for the chassis & huge heatsinks. That's a lot of machined metal that costs a pretty penny. Many people are not going to spend that kind of money anymore given the way the economy turned in 2008.