I dont know what you mean by they would be a start. Floyd's legacy is ten years deep, what do you mean by "start"? Also, when considering going up in weight, there is no historical requirement. It all depends on his natural physical growth. There is no "need" for Floyd to fight at 160 if he doesnt have the size to.
I mean just that. He has lacked serious challenge, given his (self-proclaimed and probably rightly so) talent. Well, as you might have gathered, I don't care much for him. But I'm not a hater either. I DO appreciate his talent, and despite his ten year career being very good, it falls short of the 'great' level he always proclaims for himself. He has not faced the quantity level of talent of a SRR, a SRL a Duran or even a Delahoya or a Mosley. There is NO REQUIREMENT for him to fight at 160, No. But if he is to be mentioned in the same breath as SRR or Duran, and given that he has the boxing talent to beat some (maybe all) of the best at 160, he could take the risk and prove that he is a top ten alltime great. Or he could keep fighting little guys like JMM and Pac and lesser talented welters like Baldomir or past prime welters like Delahoya or current Mosley. This might put him in the alltime top 20 or 25, but to reach the very top, he needs to take more risks. The punisher would be a good addition to his resume, even at 147.