What else could be done to the 8NR though? The calibration engineers don't like it because the efficiency and torque just don't match the benchmark. The mechanical team doesn't like it because the cylinders are just too small to work with. But it ended up being one of the most important engines in their entire lineup (in China it was what made the Corolla the king of the compacts). That engine really needs a power bump to at least 100kW and over 200N.m, all the while not losing any efficiency.
Small changes to output, responsiveness and efficiency are always possible for turbo engines, and were often done for Toyota turbo diesels.
For significantly bigger output, i expect that 1.6l turbo... depending on the market of course.