Don't get me wrong. It is possible but it all depends on how they react. Look at RG Snyman for example. Setbacks happen and recovery is very dependent on surface too. I have no doubt everything will be done correct but I really don't see Leinster or IRFU rushing him back too. They will want him 100% perfect. That extra month if needed will be better than a reoccurence or any avoidable setbacks.
I not sure if ye follow hurling closely but Ryan Taylor of Clare is a great case study. He was out 1 year almost to the day from All Ireland last year to last Saturday. His recovery was delayed because at times pitch was too soft or too hard and they need to rehab specific times on specific surfaces. And unfortunately astro is detrimental.
I just think they will side on the cautious side. And that isn't bad like he may recover fast every individual is different. But as
@big ginger 8 said it most certainly isn't the career ender of yesteryear and most actually do recover to where they were pre injury