Buying a 2k Blu-ray when a 4k Blu-ray version exists

[PCFan]

Next year, maybe June at the earliest, I think I might be upgrading to a 4K television set and a XBox One S, maybe to the XBox One S early next year and sell my XBox One. I'm hesitant to buy a 2k blu-ray when a 4k blu-ray of the same movie exists, even with the higher price of the 4k version, because I think I will be going 4k sometime next year. However, I don't mind still buying the 2k versions if the movie does not exist in a 4k blu-ray version. Also unless I want to see the movie badly, I'll just wait until I have my 4k television and XBox One S and then buy the 4k blu-ray if it exists. Would it be a good idea to slow down my blu-ray buying for the movies that are also in 4k blu-ray given my situation?