I agree they should sign exclusive deals with artists which would give them leverage in their negotiations with the record labels with an eye on the long-term hope of breaking that reliance on them.

They won't be able to get into concert tickets at the present time in any significant way due to the exclusive agreements between Ticketmaster and venues. Though maybe the could start with some smaller acts and venues and work their way up.

Live performances is where the money is for the artists which is why record labels are now signing acts up for complete deals which include not just the music rights but the concert and merch rights as well.

Edit: as somebody who has tried to buy tickets to a hot show on Ticketmaster the second they go on sale and watched the servers melt, it is Amazon that I would like to see get in the ticket game.