Labour lost last time for two reasons:
- they fell in with the austerity 'logic' of the Tories and so the party's natural constituency thought: "what's the point?'
- the media managed to persuade you southern softies that a vote for Labour was a vote for Nicola Sturgeon and the SNP
Corbyn is delivering an Old Labour programme. There's nothing too radical about it (unfortunately) and it will resonate with the population sick of the Tories IF the Judas's in the PLP get behind the LP leadership.
In any case: the next election will throw up a minority led government - so Corbyn really needs to make overtures now to the Welsh and Scots Nationalists as well as the Greens to make electoral pacts and cobble together a majority government.