But take note, we need to consider the adjustments he will do. Of course, Jon will become bigger thus becoming slower. We can't conclude that he can have the same speed and cardio when he finally enter the HW division lol.
If a fighter is not cutting any weight how come that will slow him down, he will be in the best shape of his life as he is not draining his body two days before the fight to cut the weight and it is not a disadvantage but an advantage.
It's different when you are just walking around and chillin' as a heavyweight than actually fighting. He's been fighting as LHW for years and any recent change in weight class would definitely affect how he fights in the octagon. At LHW, he can last for five rounds or even more and if he'll use the same pace as a HW in the octagon, that's going to affect his cardio. Not to mention the power of natural HWs have in their punches, it's going to wear him down if he gets hit.
It is not going to be easy when you are fighting in heavyweight but they are not that technically sound nor fast, fighting is always a mind game if you neglect the heavy punches which Jon Jones knows really well and stamina will not be an issue as i have seen him battle out many situations during championship rounds.