Really, I think it misses the point. Databases are about storing data, and admit a wide array of front ends, and there are plenty of tools now to use spreadsheets as a front-end for databases (most spreadsheets have basic tools for this built in, and more advanced ones are available.)
Spreadsheets are about viewing/manipulating data, and can both natively store data (in what is, necessarily, a database, though perhaps not a relational one) or connect to foreign sources for it.
"The next generation of spreadsheets will be a database" is a silly statement, for that reason: its possible the next generation of spreadsheets may have a particular kind of database (say, relational) as a native, internal storage system and expose tools for working with it. Or the next popular database front end -- the next Access -- may be a general purpose spreadsheet with the right tools.
And maybe spreadsheets, as a viewing and interaction tool, will be replaced with something with a different more mobile/touch-friendly UI paradigm, as the article seems to suggest (but doesn't really present much of a case for -- making vague suggestions about how spreadsheets don't work on touch [that remind me of the kind of hyperbolic descriptions of why current solutions don't work typical of infomercials] without any suggestion of what concrete elements would work better is not making that case.)