Fomalhaut
Sun - Fomalhaut H-R Diagram
Fomalhaut is in the main sequence right now and is hotter than the sun and brighter than the sun, but if you look at the H-R diagrams on each side you can see that they are very close to being in the same place as each other, so they will also most likely have similar deaths. Fomalhaut will turn into a White Dwarf star and then drop down into the white dwarfs group and eventually go black and disappear. Basically, once the star runs out of it's main source of fuel, hydrogen, it will begin to shrink because it can no longer burn anything, once it gets small enough it will desperately burn anything that it has as a fuel and will increase in size a lot until and become a red giant, it will stay a red giant until is out of all fuel sources. Once this happens, it will decrease in size and become a white dwarf star, eventually its color will drain and it will die out as a black dwarf star.
Fomalhaut Compared to Rigel
Fomalhaut - Rigel H-R DIagram
Rigel is a much larger star then Fomalhaut, it contains much more hydrogen and this causes it to burn off more then Fomalhaut, this is the reason why it is bigger. Once Rigel runs out of Hydrogen then it will do the exact same thing as Fomalhaut and most stars, it will shrink and then desperately burn off the rest of its fuel supplies, but, since Rigel is so much bigger then Fomalhaut, it contains more "backup" fuel then Fomalhaut. It will become a massive red giant quickly burning out its backup fuel, and then once it runs out of backup fuel it will have a hollow inside, which will cause the massive star to collapse on itself. Once it collapses on itself, all of the matter from the outside of the star will slam into the rest of the star causing it to explode in a supernova explosion. Once the explosion is over, the star will have formed itself into a massive black hole.