There are are techniques to create flexible PCBs. The individual ICs/components themselves are still solid but the circuitry around them can be flexible. It is currently only used in military/speciality applications to my knowledge but it has existed for a long time.
You can also make an average IC _much_ smaller than it currently is. The actual IC in most packages is tiny compared to its packaging. Its really just a matter of time and market demand till they become substancially smaller. The only components that are size sensitive are those that dissipate a lot of heat which will improve with manufacturing process improvements and passive components that need volume for their function (10uF capacitor).
You can also make an average IC _much_ smaller than it currently is. The actual IC in most packages is tiny compared to its packaging. Its really just a matter of time and market demand till they become substancially smaller. The only components that are size sensitive are those that dissipate a lot of heat which will improve with manufacturing process improvements and passive components that need volume for their function (10uF capacitor).