The attack resulted in Daniel Bryan starting the match all by himself until an injured Kane made his way down the aisle later in the match with a walking boot on his left foot. The injury hurt Kane's ability to wrestle, and ultimately, his team's ability to win the WWE SmackDown tag team titles.
Most assumed that the injury was storyline. Instead, it appears that the injury is quite legitimate.
A report from PWInsider notes that Kane suffered an Achilles tendon injury at the final SmackDown before Extreme Rules. The very real injury was the reason that WWE shot the segment backstage where the Bludgeon Brothers attacked he and Bryan. This gave Kane the reasoning to walk out in front of the crowd with that walking boot on since nobody was aware he was actually injured six days earlier.
Don't expect Kane to appear back on WWE television anytime soon. The short-lived Team Hell No reunion with Bryan appears to be shelved for the time being. WWE had previously been considering both Kane and The Miz as possible opponents for Bryan at SummerSlam. The injury sustained by Kane forced WWE's hand and it became pretty clear on SmackDown this past week that Bryan will be wrestling Miz at SummerSlam.
Even if Kane had not sustained the Achilles injury, Bryan vs. Miz would have been the right move. The duo have been building a feud for almost two years now, going back to Bryan's early days as SmackDown GM when it appeared he would never be cleared (by WWE) to wrestle again. Now that Bryan is performing again, a match with The Miz is one of the most anticipated bouts that WWE can promote right now.
While he recovers from his injury, Kane will have plenty to keep him busy. He is currently running for mayor of Knox County, Tennessee, a race he is heavily favored to win.