It's very possible that we see Taker on Raw tomorrow start to retire, only for Sting to come out, talk him out of it and have one last match for both the following year. It's very plausible, because it would seem such a waste for Sting to finally sign, only for Taker to retire which leaves Sting really with nothing left to do other than go into the HOF. Plus, the format of announcing the main event a year in advance worked wonders for WWE back in 2011/2012 for Wrestlemania 28. So business-sense wise, it would make total sense to announce Sting and Taker in their final match a year in advance. It'll make many people, including yours truly (who has a fear of flying) make the trip to San Francisco to see it.
But while all of that is possible, and I won't be surprised if that's the direction they're going, to be honest, I think this was the last one. As big as a "Retirement Match" would be for Taker and Sting, it just isn't the same without the Streak on the line. Like many have pointed out, the only reason that Taker has even wrestled in the last few years was the Streak matches. Now that the Streak is done, what is left? I definitely don't see a Lesnar/Taker rematch in the future. The match was not their best, and what would be the point in Taker losing finally, only to come back and avenge that loss? The end of the Streak basically means the end of Undertaker. Other than a Sting match, there nothing left for Taker to do now that the Streak is over. A match with Cena would've been epic. But now that the Streak is over, it wouldn't matter. A match with Taker finally letting someone new for the future like Bray Wyatt or Roman Reigns, or even Daniel Bryan end the Streak would've worked (especially Wyatt). Now a match with Taker at Wrestlemania doesn't matter near as much. Sure it's still be big to beat Taker at Wrestlemania, but which would matter more, giving Taker his second loss at Wrestlemania, or his first? Obviously the first.
Unless WWE goes with a Sting/Taker "One Last Hurrah" match for both next year, this was Taker's last Wrestlemania match. Maybe not the absolute last match, but I'd say most likely this was it. The only other thing I could see Taker doing besides a Sting match would be one last match with Kane perhaps at the Survivor Series in one more coffin or buried alive match in which Taker loses, and we finally see the end of the Taker character. But now that Kane is "Corporate Kane" I don't see that happening either.
I basically put percentage odds for "The Future of Taker" like this.
A Wrestlemania 31 match with someone new (Cena, Wyatt, Bryan, Reigns): 2%
A rematch with Brock at Wrestlemania 31: 5%
A rematch with Brock at another ppv (Extreme Rules, Summerslam): 15%
One last match with Kane to finally end the Taker character: 25%
One last match with Sting at Wrestlemania 31: 35%
Taker will retire on Raw and go into the HOF either next year or the year after: 75%
I think this is it and we're gonna see one of the most emotional Monday Night Raw's ever. On par with the Owen tribute episode. Which is why I'm calling in work to watch Raw tomorrow night. If Taker retires, I definitely want to see it.