[SOLVED] How long it may take for the GTX 1050 Ti to become obsolete for gaming?

Solution
Until it stops doing what you need it to.
Im sure there are many people out there who consider it obsolete, because it cant deliver ultra settings in modern AAA titles (hint, its not meant for that).

If you play games on it and they run how you want, then its fine. If you keep playing those same games then youll never need to replace it.
If you already have one, keep using it until it no longer does what you need it to do. If you don't have one, then you might want to consider your options before you buy it. You need to consider your power supply situation, and the kinds of games you want to run, and the resolution/settings/framerate you want. An RX 570 would be a better option as long as you can power it.
 
If you are looking to buy one new right now, I agree with WildCard's suggestion that it's not the best value option at the moment, at least when going by current US online pricing. Most 1050 Ti's are priced around $170 or more, which is arguably way too much for the level of performance they provide relative to other cards, and is even higher than what the card launched for two-and-a-half years ago. The 1050 Ti was an alright option a year or so back when there was a graphics card shortage that caused the prices of cards to rise significantly, but prices have since come down, making it a much less attractive option.

The Radeon RX 570, by comparison, is around 50% faster on average, and is widely available for less, with a few models even priced under $130 new. Or for about the same price as a 1050 Ti, you can get an RX 580, which is even faster still. The only real downside to those options is that they require greater power draw under load, so your system should have a relatively decent power supply of around 500 watts or so. The 1050 Ti is more efficient by comparison, allowing it to run on most lower-capacity PSUs, like those that come with many pre-built systems.

However, even if you have a low-end PSU and don't want to replace it, there's still a better option. Nvidia recently released the GTX 1650, which is faster than a 1050 Ti and generally costs less, while drawing a similar amount of power. Compared to an RX 570, the 1650 is still generally priced higher while delivering a bit less performance, but it is not as far behind in terms of value, and its low power draw could potentially make it a decent option for many prebuilt systems.

If, on the other hand, you already own one, it is still a capable card that should be able to run current games reasonably well at reduced settings. Obsolescence depends on what you want out of it. If you want to get smooth performance in the latest games at 1080p resolution with high settings, it's not likely to be adequate. If, however, you are fine with turning settings or resolution down, or are playing less-demanding games, the card may still be fine for your needs.
 
If you have a 1050 Ti now, you will be using that for maybe four or five years until games might need more then a 1050 Ti. For example I did a build about four years ago with a GTX 980, most high-end games now only need about a GTX 960 to run. So basically by the time you need to upgrade you whole system is went it will be obsolete for gaming, so I wouldn't worry about it. As Gam3r01 said, "If you play games on it and they run how you want, then its fine. If you keep playing those same games then youll never need to replace it".
 
If you have a 1050 Ti now, you will be using that for maybe four or five years until games might need more then a 1050 Ti.
This seems a bit unlikely, at least if we are talking about running new releases at 1080p resolution with decent frame rates. A 1050 Ti is targeting a lower-end segment than the 960 was several years ago, and it isn't even much faster than a 960. And even the 1050 Ti is nearing a few years old at this point, having come out back in late 2016. Now if they bought a GTX 1660, which is targeting a similar market today as the 960 was four years ago, I would say sure, that mid-range card will likely run new releases pretty well for several years to come, but that card is twice as fast as a 1050 Ti, and a bit faster than your 980.

Also, keep in mind that there will likely be a new generation of consoles launching next year, and it's likely that games targeting those consoles will tend to be more demanding on the PC as well. Many new releases will likely continue to run well enough on something like a 1050 Ti so long as the settings are kept in check, but expect an increasing number of games to not run all that well on that level of hardware without resorting to dropping resolution.