Well, to pick out the largest flaw in that plan, the Wraith would still have free run of the Pegasus galaxy even without the stargates, so the only effect of shutting down the network would be to strand the indigenous human populations, preventing them from escaping wraith attacks, making diplomatic partnerships, or engaging in the interplanetary trade that they no doubt depend on to survive after living with it for at least ten thousand years. So that's pretty much just being a DB for no reason.
The Human populations don't want the Atlantis group, an upcoming episode of season 5 is going to make it clear all of them want the Earth group gone.
The Asurans have been destroyed, the Wraith will tear themsevles apart and whats left will take Micheal years to consolidate and turn into an effective task force for him to use, if at all.
At that point should they try and get to Earth it will be many years down the road, with the entire 304 fleet, 3 Aurora's, Atlantis, hundreds of 302's, the Ancient weapons platform, the Free Jaffa Nation, the Tok'Ra, Lucian Alliance standing between him and victory.
Without Stargates, Pegasus is basically a few dozen Human worlds that are very ungrateful and want us gone, and the Wraith in the middle of a civil war. Whatever Wraith make it as far as the Milky Way are fucked.
Be lucky I didn't go ahead with Plan A. Pretty much the Plan B above only with the added effect of sending a massive viral infection throughout the galaxy then shutting down the network, euthanising the entire population of Pegasus as Atlantis leaves for home.