Well, the market has left Pizza Hut behind.

With delivery, why go out to a cheap pizza restaurant?

Having a sit down restaurant is expensive, even if the building is paid for.
You need servers, and someone to clean the whole place.
Even heating costs more.

So, today, people consider pizza one of those things you order delivered.
A place that is basically only an oven is far more economical.

So, with continuing trends, either Pizza Hut goes high end, or goes low end. Their place in the middle is killing them.