Are there any alternatives?

The RTX 3070 and RTX 3080 are both good alternatives from Nvidia. The 3070 Ti is wedged right in between the two, and provides equally good performance for the price. On the AMD side of things, the closest competitor is the $649 Radeon RX 6800 XT.

　　

How long will it last?

The RTX 3070 Ti should keep your rig up-to-date for upward of 10 years. It supports the latest technology and screen resolutions, and should ensure that PC games that come out five years from now can still be played.

　　

Should you buy it?

If you can find it at (or near) retail price, buy it.