The analysis out this morning from Barclays Equity Research captures the general ambivalence on the Street about the eagerly anticipated Apple television set, which the firm expects to see as early as 2013. It envisions a TV set that blends Internet and conventional TV programming enhanced by features including Apple’s Siri voice controls and an iSight camera and microphone. “Apple’s eventual television could be so much more than a TV — including gaming, video communication, content delivery, apps, computing and all the capabilities of the current Apple TV — that it is really not fair to compare it to products already on the market,” Barclays says. The TVs probably wouldn’t need to be connected to a cable set top box; they could use CableCARDs to unscramble the providers’ signal. Although that would mean no access to the operator’s VOD, Barclays says that consumers won’t mind because they’ll be able to connect to services such as  Netflix and Hulu. Barclays estimates that Apple could generate $17B in revenues it it takes 5% of the TV set market.

But Apple won’t revolutionize TV because content providers have too much invested in keeping the current system intact. Cable networks collected about $28.9B last year in fees from pay TV distributors, and Big Media will “vigorously defend the bundle,” Barclays says. Even if Apple could cut enough deals with programmers to offer a replacement for conventional pay TV, consumers “would need to replace every TV in their house with an Apple TV.” And cable operators can always play their trump card: fiddling with caps for broadband data usage, or charging subscribers based on how much they download. For example, Comcast’s 250 GB a month cap would limit users to 125 hours of HD programming a month, or about four hours a day — less than the five hours of viewing in the average U.S. household. While not a game-changer, Apple may have to be  satisfied offering “the entertainment hub that others have aspired to become.”