he was waiting for someone and that someone has not yet come (actually Luffy did come already but he's not there just yet), wb also meant that BB might have killed him, he might become extremely OP, he might have known BB was gonna take his DF and go on a DF hunt, he knew BB will go and cause havoc for the world ... but he was consoled by the fact that at the very least Marshal D Teach is NOT the D that Roger was waiting for because he realized that the one who will challenge the world anf find OP will be Luffy the one who carries on Rogers will and the brother of Ace
''It's not you... The man Roger is waiting for at the very least, Teach.... It's definitely not you. Just like there are those who carry on Rogers will , I'm sure somebody will appear to carry Ace's will, someday.Even if you extinguish his bloodline ; there's no way that their flame will ever burn out. It has been passed down since ancient times, and in the future , someday , somebody (Luffy, NOT Teach) will appear carrying the history of all those decades on their back, and challenge the whole world to a fight. Sengoku, you guys in the world government, all fear that immense battle engulfing the whole world : that will eventually come! I don't care myself... but as soon as someone finds that great treasure... this entire world will be turned upside down! And someone WILL find it. That day will definitely come sooner or later.''
