You might think the share holders. Not correct. Though they don't lose.
Think: the law firms handling the deal. This type of deal is worth millions in fees; banks - both investment (for finding the cash) and traditional (for providing the cash); and the governments which would levy taxes and fees. And of course anything below the public view (kick-backs, trips, outright campaign donations). I mean it's no surprise they picked a campaign year to merge. ;) The companies have probably been talking about this for at least a year.
It might not go through. If there is enough back lash from other companies. Happened with ATT recently. What will matter are other content providers (Disney, Fox, Viacom, etc etc) - though it wouldn't surprise me if they get certain guarantees they we won't know about.
Netflix doesn't really have any muscle on the ground to fight this. But if they could form a coalition of sorts, with the likes of Amazon, Google, Apple, FB, Twitter, (maybe even) MS and Sony (they have a stake in this too), etc, etc - combined they'd be a formidable force that Commcast/TM would have to deal with.
And then there's us. But I hold little hope for the american public to rally around any cause. Plus too many are too easily swayed.
My hope lies in a the coalition of net companies I mentioned.
At first, the deal makers: executives, bankers, lawyers, auditors, consultants and assorted advisors.
Down the road... nobody.
Not really much different than how Comcast and TWC are individually competing right now (as their service areas don't overlap). Though I'm not suggesting either one is a shining paragon of customer service or fair pricing (I don't have any first-hand experience to speak of there; I'm in Canada).
It certainly feels like little else than a handshake deal to create a monopoly.