Barnes & Noble is not opposed to buying their way into a business. Remember, they bought Fictionwise and eReader way back when, and then used those companies as a platform to launch the Nook. B&N also owns Tikatok, a service that encourages children to write their own stories. You might recall that some time back tikatok released an app exclusively for the NookColor.
So this idea isn't entirely out of the question. And it would give B&N a solid established presence in the UK book market. They wouldn't just be an outsider, like Amazon; B&N would have established a desire to be a partner to UK publishers and authors.
But I don't see it happening. Frankly, B&N doesn't have the funds to buy Waterstones - not if they want to use those founds to expand their digital business. And I would think that B&N already knows that digital is the future, not opening more storefronts internationally. (Actually, Borders went that route and virtually all the stores Borders opened in the US, UK, and Australia have since gone bankrupt and closed.)
Now, B&N could go for a stock swap, but I doubt that would appeal to Waterstones' Russian investors. They've sunk £53 million into Waterstones, and we don't know if they want to trade that for a bigger but riskier chunk of B&N - a company that hasn't turned a profit in a couple years now.
But it's an interesting idea, isn't it. Do you think it could happen?