Bigger batteries are an option. After all, their energy density keeps improving. Nokia used to use a large battery compartment to accommodate different battery sizes depending upon their current market cost.
As for single chip solutions, they are expensive, the development time is long and requirements are changing all the time. It's better to mix and match to find what you need. Each company has different power management strengths and some companies offer dirt cheap prices for common parts.
This is short and concise article,and provides very useful information on which power consuming parts of mobile devices. Isn't it nice if there is a single-chip power management solution for all these parts?