Yes he is. He's been playing world class football for X amount of years straight and at least five of those years he's been out of this world. A shame he ran out of gas in the World Cup (QF and forward).
Messi has made players like Xavi and Iniesta appear as secondary. When Messi is "poor" he's still world class or on its fringes (see World Cup 2014 for example). When he retires we will all be glad to have been around for his and Ronaldo's era. He will be talked about as one of the greats for years and years.
Good post and absolutely correct that the Messi/Ronaldo era will be sadly lost but not easily or ever forgotten..
True transcendents.