How likely is that the next big earthquake (and tsunami) will hit the Philippines again?
The likelihood is 100%, but we don't know when. It could be tomorrow, it could be in a year, or it could be in 100 years. Make sure you are prepared for such an event.
The Philippines are situated above a subduction zone (the Philippine trench), so an earthquake is inevitable. However, it is impossible to predict exactly when and where it will happen.
As for tsunamis, these propagate from earthquake epicentres, so the Philippines are susceptible to tsunamis generated elsewhere in the area.
You are drawing a line between the Bali and Palu events, and suggesting that the next one will be along that line. This is not how it works. The earthquake could be on the line (by chance), or it could not. There is no way of predicting.