84
How has it taken this long?
(www.bbc.co.uk)
This is a most excellent place for technology news and articles.
All indefinitely means is "not certain". So it could mean a week... Or a century.
These disks are pretty well understood. You should be good for a decade. At about 12-13 years it's risky and anything after 15... If it's still working, count yourself lucky.