This comment was only noted in the Gospel of Matthew.  Not in Mark's---the first Gospel written nor in John's the last.  If this was such an EATHSHAKING pronouncement---it should have been in at least one other Gospel.  

Jesus didn't set out to establish a church.  NO apostle believed that either.  They saw themselves as Jews completely.  AND they believed that Christ would come again in their lifetimes----so why found a church?  They saw their ministry to be what Christ commanded---"Go preach the Gospel'.  Jesus didn't state "Go set up the governance structure of a church" [which they wouldn't even know anything about]. "Ekklesia was a Greek term---not Aramaic or even Hebrew.

It took until after the Apostolic Age---before the Christian communities began to see that Jesus may not be coming back that quickly.  What do you know about the second Pope---Linus?  I bet next to nothing [as with most Catholics].