Sorry, but no.
Unless the Colts want to eat $1.2 million in dead cap by releasing Vinatieri, it's silly to suggest that an undrafted rookie is going to supplant arguably the greatest kicker in NFL history. Though, if it happened, the irony would certainly be interesting. Vinatieri went undrafted out of South Dakota State and signed with the Amsterdam Admirals of NFL Europe in 1996.
Why would Indy want to dump Vinatieri?
It wouldn't be because of performance. The guy attempted more 50+ yard kicks last season than at any time during his entire career. Of the seven he attempted (career high), he made four (also, career high). He was also 9-10 from kicks between 40-49 yards and made all his PATs.
Without Vinatieri's 53-yarder against the Vikings in the 4th quarter of Week 2, his 43-yarder in the 4th quarter of Week 9 against the Dolphins, or the 53 and 40-yard kicks he nailed in the fourth quarter against Titans in Week 14, the Colts do not make the post-season in 2012.
You want to get bitchy that he made only 4-7 from 30-39 yards in 2013? Fine. Whatever. The dude is a legend. Hardly a reason to cut him for some nobody. When a game is on the line and the Colts need a big 45+ yard field goal, I'd still trust Vinatieri to make that kick over 95% of the kickers in this league, including the guy that replaced Vinatieri in New England: Stephen Gostkowski.
For those of you hell bent on seeing Vinatieri gone - personally, I think there's something wrong with people who want this, but whatever - he is in the final year of a three-year deal he signed in 2011. At age 40, this might be it for "Vinny." My hope is he goes out on top with another ring, and he wins it by making another big kick in a Super Bowl.
As for why Brandon McManus was signed, he'll make all the kicks in training camp and preseason. This way, Vinatieri's leg doesn't fall off mid-October.