I think the Liberals would bnever back Ford but a coalition with the NDP would be fragile and politically problematic.
Serious question: Why do you think the Liberals would never back Ford? Is that more credible than them never voting to prop up Harper (or saying they'd be Harper's worst nightmare and then crossing the floor before the House is even convened, say)?
The Liberals in Ontario doubled down on the direction taken by Wynne. The conservatives doubled down on a move to the right. Under normal conditions those parties are much closer than they are today. the Liberals are very unlikely to dump a leader and do a 180 to Ford -- I think they could have with Elliott. I think Ford is far too extreme for the Liebrals to work with - without doing lasting damage to themselves. All three parties are probably terrified tonight even though they will not all suffer it is unclear which ones will:
The NDP risks a stampede to Liberals by swing voters and NDP switchers. I think that is almost 1/4 of the total vote so that is a make or break number.
The Liberals risk, if they fall below the NDP having that stampede go to the NDP. This is especially true since they are a tired government and even some Liberals may be happy to see the party go into opposition. If they calculate wrong this could be an existensial decision - at least for a generation.
The Conservatives need to fear that while exciting their base Ford could get a victory or he could instead drive away enough of the swing voters that if the gravitate to either hte Liberals of NDP, the Conservatives could effectively defeat themselves -- again.
Yes, Ford will shake things up. But without knowing how each party will behave, it would be wrong to count out any of the three parties or make presumptions about which will take the advantage. This is what polarization looks like.