In a reimagined prequel, Obi could already be a full Knight so it's no issue. Yoda will have trained him before the events of the films :)
The Prequels as they already are has done more damage than that by introducing Qui Gon as Obi's master, contrary to what we were told in the OT - and then Lucas awkwardly tried fixing it by implying that Yoda is like a freaking Kindergarten teacher for all young Jedi......yes, that makes it all better, George.