The long term geological fate of Io depends on the complex gravitational dance between the moon, Jupiter, and the other Galilean moons. Io is currently the most volcanically active body in our solar system because tidal heating generates massive amounts of internal friction as Jupiter's gravity stretches and squeezes the moon.
Current scientific models suggest that this process is not a permanent state but rather a stage in a long evolving cycle. The heating is driven by an orbital resonance with Europa and Ganymede, which keeps Io in an eccentric, or non circular, orbit. As long as these gravitational resonances exist, tidal heating will continue to power intense volcanic activity. However, if the orbital configuration changes over millions of years, the heating could diminish.
While the heating is intense enough to drive extreme volcanism, it is unlikely to deplete the moon's core energy entirely on a short timescale. Instead, the interplay of orbital mechanics means this cycle can remain sustainable for hundreds of millions to billions of years, provided the orbital resonance remains stable. For more detailed planetary data, you can visit NASA at https://science.nasa.gov.
