Have been thinking about this thread for a couple of weeks now and wanted to share my thoughts.
I agree that a resolution bump up should come quite soon with 4K right around the corner. The standard for blu ray discs in 4K TVs has already been set and blu ray players to support them are coming out by the end of this year. The problem with 4K TVs has been that there hasn't been much content for it outside of Netflix and a few other services, but I think that is set to change by next year and it wouldn't hurt to adjust accordingly. The question is how do we adjust?
First off, I agree with Nopealope when he says that 7mb+ file sizes are insane and regardless of the resolution jump, the file size should sit around 1mb at most. I don't have a massive collection of movies or tv shows, or a massive amount of storage to even store the content if I wanted to. I upload stuff for fun.
I truly do like the way that TMDB allows uploads by ratio. For Fanart.tv, I think we could implement something similar and here are some brainstormed rules of how it would work:
1. Minimum for each upload, regardless of category, would be the set standard as it is right now on Fanart.tv, so posters would all need to be 1000x1426 minimum and HD Clearart would be minimum 10000x562.
2. All old content that doesn't allow uploads any longer should be merged with HD version of that category(HD Clearart & clearart should merge for example). Similar to how language is selected for a piece of artwork and how it is displayed for each artwork on the site, the quality of the image would be listed as "HD" or "SD". There is a reason I recommend this for the system to be similar to everything else, keep reading.
3. There should certainly be a maximum resolution for artwork as well. No need for 8000 pixel wide posters. Maybe the new system could have a dropdown when uploading and you can select whether the image is 1000x1426, 1400x1996(comes from 1400x2100), or 2000x2852(comes from 2000x3000). All posters would remain under the poster category, they are just assigned a title similar to languages, so 1000x1426 could be "HD", 1400x1996 could be "QHD" and 2000x2852 could be "UHD". This concept could be applied to all categories, not just posters.
If we link everything when uploading by ratio, then we could have various resolutions in between the two new resolutions I mentioned which could led to a couple of problems in the future. By defining what the new resolutions are while maintaining that we could still upload at standards that are implemented right now as well(such as 1000x1426 as minimum for posters), I believe this new system will help future proof the site and prevent the need for future HD categories for sections such as "HD Posters". (Until 8K becomes a standard that is in like 10 years lol, then we could just add a new resolution or two to the dropdown of the new system)