Reflections - Download and if you like it buy it??

By searching music sites online I stumble into many sites with links to download full albums.
Their excuse is "Download and if you like it buy it"?

Is this a valid excuse?
It is sure a good and cheap way of meeting new bands.
But will anyone who has downloaded an album and liked it go to the record store and buy it?
I don't think so!

I agree that it is a good way to extend bands fan list. But they will not get the right profit over it.
How would a band obtain their rightful credits?
Future albums? Not if they continue to be available for free download.
Merchandising? Yes maybe. . .
Concerts? Yes! If you like a band you will certainly go see them live.

Will this be the future of music?
Will bands be able to survive with concerts?

I will eave this questions open. . .