Sure Myspace is troubled, just let go of about half their staff and will likely be sold off. Obviously Google, Microsoft, Yahoo and AOL come to mind as acquirers. Google could potentially avoid antitrust concerns because Facebook is such a force in social networking but merging disparate back-end systems would be a nightmare for company who counts computing efficiency as one of its core strengths. Microsoft makes a lot of sense but with a financial stake in Facebook, this may not make the most sense for the company.
AOL and Yahoo would likely choke on the acquisition and both companies have full plates as it is.
Twitter though makes a lot of sense because they need to compete more effectively with Facebook who redesigned their home page a few years back with a status update field to compete more effectively with the microblogging service of 140 characters or less.
Of course the challenge is a revenue model and there is no simple answer to the problem. I still haven’t seen an ad on Twitter and if I've witnessed a sponsored tweet I wasn’t aware of it and didn’t click on it. But if we ignore the financial perspective we see it makes a great deal of sense for Twitter to merge its offering with Myspace to instantly create a full-fledged social network with the combined user base of both companies.
Twitter is hot right now so they can subsequently drop the Myspace name and turn their sights squarely on Facebook. And they better move soon before they have to contend with Apple as well.