SoundThumb, I was going to make the same point. Most of the pianos I service are flanked by Keyboards. Just about every pianist, amateur and professional, have both acoustic and digital. With, of course, a spattering of synthesizers. The "mini moog" seems to be very popular item these days.
I find digital pianos with acoustic as well, however, teachers report that 50% of their students only have a digital piano, or worse, a small keyboard. A piano store reported selling 75% digital, 25% acoustic. Digital are the Spinets of yesteryear. The "starter" pianos.
Yes, acoustic piano sales will climb as the economy improves, but acoustic pianos are still on a long term, decades long, downward slope. 200,000 per year in the 1970's to 35,000 per year today is a downward slope in acoustic pianos - especially when you consider population increase since the 1970's. In contrast, digital piano numbers climb higher each year.
I would have to see a lot more than 35,000 acoustic sold in a year to call it a growth market.