This is a big problem. Firefox dropped Gopher and Chrome never supported it. Most Gopher users, presumably, use a Gopher web proxy.
For fun I recently built a Gopher web client, implementing the entire protocol in a single page app (literally a single HTML file, no frameworks or dependencies). It supports most documented file formats including "modern" extras like video and audio.
Gopher client: - https://gopher.commons.host
Source code: - https://gitlab.com/commonshost/gaufre
Flash also works if you are using Chrome. Sadly, Firefox does not support Flash plugin anymore (and i say sadly because just yesterday i was trying to find some files from an old site that was made using Flash and i had to use Chrome just for that).
There's also the question of hardware, but so long as we have at least one up-to-date PC emulator, we have an answer to that. It might become more of a challenge going forward, as mainstream emulators drop BIOS support and other legacy parts of the platform; but even then there's stuff like PCem.
There's also the problem of consuming old internet content. Do you still have a gopher client? Will old web pages look the same in your browser as they did in 1995? Flash will no longer work (hooray?).
On the other hand books, photographs and magazines stick around until you throw them away and we have public institutions that are dedicated to their preservation.