Yes, in general, I think those days are numbered. However, the major labels will continue to base their business models, wrong or right, on selling music, until their dying breath.
If MGMT were an independent or unsigned band, I would tell them to put it up for free download in a heartbeat. As other people have mentioned, it could be a good idea have the fans submit an email address for the album (or half the album), and build the email list. Then you can reach out to them later and upsell to a higher price point or tell them about tour dates.
HOWEVER, I don't think Sony would never and will never do that as long as they are a major record company. As far as I know, MGMT doesn't have a 360 deal with Sony, and thus, Sony is making no money off of the band's ticket sales and merch sales, only recorded music. Until that changes, they will want to sell as much music as possible.
"Because it already is free. So why not try to take advantage of that to actually make some money by embracing it and feeding it into a real business model?"
But by this logic, why should bands bother trying to sell their music at all? I think you could make that argument for any album out there today.
If I were the band / label, I would put up a cheap digital download today (or pay-what-you-want). Give the fans a simple, easy, quick way to pay for the music (digitally, or up-sell for a premium package), and I think you'd be surprised at how many pitch in.
I don't think bands are crazy in thinking / hoping that people will pay for their music, and I think Sony and the band should put the album up FOR SALE now. If I can throw $7 towards the band today to legally download the album, I'd happily do it.
I love all your pieces, and generally agree with you, but not here. Sony most likely paid for the recording, production, and marketing for the album. Why on earth would they give it away for free? I'm all for bands giving away their music (I think the days of recorded music being the final product are numbered), especially independent artists as a way to boost ticket sales, merch, premium physical products, etc., but in this situation, it makes absolutely no sense.