We don't know that for sure. Cricket is a game of gloriuos uncertainties. Look at the West Indies, they were a excellent team up until the early 90's. At that point, Haynes ('94), Greenidge ('91), Richards ('91) , Dujon ('92), Marshall ('92) all bowed out around the same time. The West Indies then went into a rather sharp decline...
Indeed but the warning signs that the next generation weren't up to the standard of the previous were there years before any of them retired. Whenever the WI team tried to blood some new players, they inevitably failed but the greats being still in the team covered for them. Players such as Philo Wallace, Ezra Moseley, Carlisle Best, Anderson Cummins in the late 80's/early 1990's came and went quickly with brief flashes of brilliance, which should have been warning sign number one.
Warning sign number two should have been the impending retirements of Viv, Dessie, Gordon, Duj, Marshall. Simple as that. Losing half of your great team in combination with observations of what was on the way up should have registered as a potential problem.
When players such as Stuart Williams, Cameron Cuffy and others came through the under-age groups and people saw that these guys were somewhat lower-class than those they followed, it was too late. The greats retired and what was left were players barely of Test standard in combination with a few of the greats still left as well as those who were fairly decent (I'm speaking of the bowlers primarily here because obviously Lara is a great and Chanders, Arthurton and Jimmy Adams at one stage were very good too). It was enough to get by until the Aussies finally nailed the pretenders in 1995. Curtly and Courtney were baulking somewhat at having to not just lead the attack but to shoulder the responsibilities of the others too and it showed. For example, in 1995, Curtly didn't have an impact on the series until mid-series and that was on what could be termed 'under prepared'; a green-top in other words. Before and after that match, he was solid but unspectacular.
Mind you, the WI also had a shocking run of career-ending/damaging injuries to potential greats like Ian Bishop and Phil Simmons. That would have set them back quite a bit too.
The point is, the Aussies are learning from the WI example and the new crop are introduced slowly having paid their dues at state level (with a few exceptions). This is something the WI did not do and they're still paying for it, particularly in their bowling stocks (as the batting is recovering much quicker with Sarwan and others looking quite promising).