Good post mate. However I think Conservative administrations have historically run bigger deficits than Labour ones but that doesn't really help us in this situation. The point I think I'm trying to make is that austerity probably wasn't needed to the level it has been imposed. Even Osborne realised he'd got it badly wrong. Classic Keynesian theory would have seen an increase in net debt but with the money going into the public sector. Instead it mainly went into propping up the banks and has come out of public services.
I think the public did accept the concept of austerity (wrongly) so they did get the message across. But as you say there's been no vision about what post-austerity will look like or even when it will happen. Even if we achieve a balanced budget then debt is still way above the 40% of GDP that is considered the acceptable level these days and growth is slowing down dramatically and is now the weakest in the EU, whatever SWP's Back may say. So the only alternative is not a more centrist view of austerity but an alternative view of where society is going.
I can understand that point of view, and indeed have some sympathy with it. But I don't accept that austerity was completely unnecessary (not sure you meant to say that, but your 2nd paragraph ("wrongly") implies it). The vast amount of money splurged on propping up the banks was totally unavoidable: there was no alternative, since the big banks going under would have had devastating consequences for all of us. And that having added to the deficit that Brown had already created pre 2008, put us into a position where we simply could not at the time just borrow even more and carry on regardless. That said, I have some room for debate about whether the cuts were too hard and too deep and whether it's time to ease off now.
Incidentally, I am pretty sure in my own mind that the reason our growth has dropped back recently is simply because of Brexit. Businesses are sitting on the fence and not investing until they know how the land lies. That's something I've noticed from a very personal perspective in my job hunting: the jobs market in my sector is very quiet indeed - more so than I can remember in a couple of decades in fact.
This in itself probably adds to the argument that now is the time to start to inject some more public funding into infrastructure and public services.
In terms of where we go from here, I think there's 3 things the Tories can do, two of which scare me.
1. Pretend nothing's happened and carry on regardless.
2. Reflect on the wave of resentment regarding the state of our public services and make tangible policy changes to address the concerns of those moderate voters who were tempted by the Corbyn message.
3. Allow the far right in the party to take the party even further right.
Imo, 1 would be completely wrong and would inevitably lead to an early election and a probably defeat.
3. would be an unmitigated disaster and leave the Tories in opposition for a decade or more. It's an unthinkable option, but one that some idiots on the right of the party will be angling for: "We need to show clear blue water and a return to core Conservative values. Margaret Thatcher won 3 elections and look at us now...", type bollocks.
2. is the overwhelmingly sensible option. Listen to the people for they have spoken. I don't believe all of those who swung towards Labour, did so without reservations about just how left wing Corbyn is. And I think the Conservatives should try to win those votes back.