[hawkice]

I'm not sure that "Why?" is always going to be a physics question, but certainly even after we understand the smallest building blocks, we will need specific models of arbitrarily complex systems where the basic rules are computationally infeasible or resistant to simple analysis.

Of course, understanding the true and most basic workings of nature will also take a lot of work, just not a literally infinite supply.

[eru]

Thanks to chaos, we will probably have no shortage of computationally infeasible systems.

Though the study of those systems is often labelled by something other than 'physics'. Biology or Chemistry or Psychology or Economics etc.