Just a few things to ponder.
1080p TVs have been with us for close to 10 years now. As of 2015, US stations only broadcast in either 720p or 1080i. What makes you think there will be any 4k broadcasts in the near future? We still do not have 1080p broadcast.
In order to get 1080p, you need streaming services or a BD player. Yes, there will be some 4k streaming on Netflix at a higher cost and will require more bandwidth which some may have to upgrade to be able to use.
Upscaling is a bit of a misnomer. You are taking one pixel of information and letting the TV extrapolate how to chop that into 4 pixels to make it look smooth. You can not get 4k form a 1080 source.
At normal viewing distances, a person can not discern the difference in RESOLUTION of a 4k set vs a 1080p one. What we can see in a difference in contrast or color depth. Manufacturers put the most and best features in their high end sets and they are all 4k. That does not mean that the pictures from their low end 4k sets are any better than a 1080p set.
You need to compare TV to one another with the same feed. Those demo loops are designed to make those sets look really good. Also, look at them at YOUR viewing distance, not with your nose against the screen.
The next real difference in picture quality will be in HDR, OLED or other screen technology. As of now, standards are not set for HDR so any "HDR compatible" TV you buy today may not be able to take full advantage of HDR when it becomes available. HDR will require less bandwidth than 4k so it is more likely to be available.
If you can find a good 1080p set with the features you need, it is all you need at this point. You can put the money saves toward the next great thing.