How long will be 8th generation of xbox consoles (xbox one s and one x) supported?

Nobody knows for sure but it’ll probably be for another 2-4 years

Console generations usually last for about 7-8 years. (But are supported for much longer than that. Xbox 360 is 15 years now. There are just no new games released anymore.)

If you're asking when a newer model of Series X/S will be released, no one knows at this point. My estimate would be about 3-4 years until we see slightly upgraded "slim" models.

The Series S is great value if you don't need 4K. So yes, I think it's worth it. 3 years is a long time to wait...

The Xbox One S is a variant of the Xbox One console. Xbox Series X/S is the newer generation of consoles. Xbox Series X/S enhanced games are only for the newest consoles not the Xbox One S. You would need to purchase the Xbox One version of the games not the X/S version of them.

Yes, it is likely that your Xbox One will not be compatible with the new Forza Motorsport dashboard update or with game updates in general, as Microsoft is focused on the new generation of consoles, the Xbox Series X and S. The Xbox One is no longer being updated and Microsoft has already announced that it will end support for the Xbox One, but has not yet said when.

Elaboration:

Xbox One at the end of its cycle:

Microsoft is increasingly focused on the new generation of consoles (Xbox Series X and S) and, therefore, support and updates for the Xbox One are being reduced.

New dashboard update:

It is likely that the new Forza Motorsport dashboard update, or other game updates, will not be compatible with the Xbox One.

Focus on the next generation:

Microsoft has already announced that it will end support for the Xbox One, and its attention is directed to the Xbox Series X and S, the most recent generation.

System updates:

Your Xbox One may no longer be receiving system updates, or the updates you do receive are only to ensure the security of your console.

Good day

All Xbox one games will work on the One S and the One X. As they are the same generation of console.

Xbox 360 games that is backward compatible will also play on the Xbox One, S and the X.