I have copies (and more copies) of all my stuff on here and anywhere else. I'd prefer HubPages go on for a long time, but I'd be fine if it closed down. People who put writing on other people's sites (like writing sites) need to be aware that they don't know what could happen and need to take steps to protect themselves and their work.
I don't think so much in terms of the site's closing down, but with changes that are always going on; I think in terms of suddenly getting a zillion e.mails that say (essentially) "We unpublished your stuff because we don't want that kind of Hub on the site any longer." It could happen. So, again, writers need to keep in mind that sites change (and sometimes in a way the members don't like), get sold, and/or close down.
(Everyone ought to also keep in mind that computers die, flash-drives get lost, disks become obsolete or lost, online storage sites/features can change, etc. etc. It pays to be a little bit "paranoid" when it comes to having done a lot of writing and preferring not to have to write it all again.) :)
Also, reminder: When applicable, keep URLs for reference/research sites, videos you may want to use again, a copy of your profile(s) in MS Word (so the links remain intact), etc. etc. - not just the copy of the Hub, itself; or just the text boxes. (I also keep copies of any answers on here that take a little bit of time/thought, and any longer forum posts that take time/thought. There's always the chance I'll want to do something with them, even if it's not pasting them somewhere else.)