Maybe a use a google drive folder? Users can download entire folder as a zip, or reference specific links to specific items. An item within google drive can be "replaced" or "updated" while retaining the public referencing URL path.
Alternatively a torrent? Though not updatable. But a torrent of a collection, updated once per month or every few months, would work wonderfully, say "TVLogoDB-20181130" (YYYYMMDD, for easy sorting), then your upload would only be whatever you set your client maximum to be (set in "initial seeding mode").
I wonder how some place like github would do for hosting a collection of logos, publicly editable.
Lastly, you could pitch to all the hosted companies to provide a donation, or provide "thumbnails" for each broadcasting company, and ask each for a $2-10/mo maintenance fee to host publicly available ad-free high quality images they provide. Write a single letter, include links to presently available site and a paypal link, batch parse each company name and address from a spreadsheet into it, send as emails and presto
I can try hosting the zip file for a while in my Google drive if you send or link it? (and permissibly attempt to upload by torrent?) If I'm able to I'll send back a link on here, maybe you can post the link on logodb site. idk, just spitballing here.
