[jeffreyH (OP)]

If one year we suddenly had no more nuts how many species would be struggling for food? How many depend exclusively on nuts?

[Colin2B]

New theories would die off very quickly.


In the animal kingdom many nut eaters are not exclusively so in areas where nuts are seasonal. Problem for them would be that nuts are high in fats so energy dense and finding substitutes would be hard.
Some birds are very specialised - specific bill shape - and might have trouble adapting, I suspect it's worth looking at those to see what might be vulnerable. Despite its name the nuthatch eats nuts, seeds and insects.
This seems quite specialised http://www.bbc.co.uk/programmes/p006txss

[chiralSPO]

New theories would die off very quickly.

LOL!

Look up "acorn masting." As I understand it, oak trees are able to coordinate how large their acorn (nut) yields are, so that some years there are far more acorns than could possibly be eaten (around here squirrels do most of the eating), allowing them to take root in high yields, while in other years, the trees collude to produce very few acorns, preventing population booms of acorn -eating animals.

Most acorn-eaters have other options, so extinction is a highly unlikely outcome for a single year of restricted supply. But a sharp drop in the amount of available food in nut form would surely impact the population.