Some other regions, lalo na sa bandang south, have a tradition of eating ground-up corn (apparently, corn grits) cooked in a similar manner to rice. It takes a bit of getting used to, but after that, it can be a substitute.

This is how it looks like when sold and this is how it looks like when cooked. It doesn't look that different from rice, if you're willing to look past the broken kernels and all that entails.

However, hindi siya uso sa ibang lugar and I don't think people would take to it easily. Thus, not many people would even bother distributing it, much less getting the facilities needed to make it in other areas. Also, do we even have enough corn for livestock feed and local consumption?