Corbyn at least has one thing that Labour under Ed Miliband didn't -- he offers a genuine alternative to the current approach. That this alternative is potentially disastrous, backwards-looking and filled with goodness knows what other dangerous consequences may not matter, if in the next four years the Tories make a mess of things. They certainly have plenty of chances to do this. The party is likely to expose its own divisions once the EU referendum rolls around -- whatever the result, you can bet that the Eurosceptics in the party won't be thrilled (probably boosting UKIP rather than Labour, though). Then there is the coming full introduction of the latest benefits system, Universal Credit, that is likely to end up pissing off all the poor people because it is a poorly-designed and poorly-implemented fiasco (not to mention being already massively behind schedule, although good luck getting IDS to admit this). Etc etc...
Of course, if these things do end up going better than expected, it's bad news for Corbyn. The Tory party need not fear him, anyway, and should just ensure their own house is in order. If it is, more than enough people will seek continuity rather than a radical departure, and Corbyn's Labour will be sunk. And, if they mess up, then who can blame the electorate for wanting to try something fresh and radical?