Australia's current fast bowling depth (with Lyon providing good support) is certainly impressive but other nations have had eras when they could boast impressive bowling depth.
Top of the list would have to be the West Indies. Their depth over two decades spanning from the mid 70s to the mid 90s is without equal.
Starting with bowlers such as Roberts, Holding, Garner, Croft, Daniel and Clarke moving to the likes of Marshall, Ambrose, Walsh,
Patterson, Bishop, Davis and a two Benjamins says it all. How many others were waiting in the wings?
South Africa always seem to have good fast bowling stock. From the 60s when they had Adcock, Heine and Goddard through to an era when Steyn, Philander and Rabada shone there have been many greats such as Donald, Pollock (2), Ntini, Kallis and Nel.
While England's current crop of quicks is impressive, I believe their depth (in both pace and spin) was at its best in the 50s. Providing the new ball attack were Bedser, Statham and Trueman (all holding world records at various times) with Tyson reaching great heights in one Ashes series and pace support coming from Loader, Bailey and Shackleton (The latter two more medium than fast).
The spinning depth was impressive with Laker, Lock, Wardle, Appleyard and Tattersall all having averages modern spinners would envy.