I think Baldwin won't get very far in talks with Labour, given that MacDonald might not even be leader of the Labour Party and he only felt compelled to enact austerity due to "the greater good" and being in office at the time - being in opposition will colour his perception the other way.
The Liberals, led by David Lloyd George, are not likely to enter into coalition with Stanley Baldwin, to put it mildly. The party would run on its Keynesian manifesto and there'd only be the dissent of a small number of 'National' Liberals. Even then, that small faction didn't exist until 1931 and the crisis of MacDonald's economic direction, as even John Simon (the man who led the National Liberals IOTL and was their most influential figure) was on Lloyd George's pro-free trade side in 1930. So, here, we have more issues for Baldwin's coalition dreams.
And, finally, the Conservative Party itself was plagued with divisions. The issue of free trade vs protectionism had split the party for three decades prior to the Great Depression and there were many for whom it was an issue worth fighting a civil war over. Just look at the OTL attempts by protectionists to coup Baldwin during the '29 to '31 period and you'll see how fragile the Tories were on this issue. Baldwin was one to tread lightly and carefully around the issue, but this wouldn't cut it whilst in government and whilst facing the Chamberlain brothers and the press barons on the vehemently pro-tariff side of the argument. If he isn't out by 1931 and replaced by a tariff reformer, then he would be walking into a general election by 1931 or 1932 with a divided party and a non-committal approach to protectionism. This could only lead to disaster.
All in all, it's best to conclude that Labour wins a majority and whoever is leader at the time becomes PM on their own terms without a "National Government".