Tend to agree its hard to see all the eventual outcomes but certainly Id say the probability of leaving on March 29th with no deal would be higher than any of the other permutations... and to be honest if Mays deal gets voted down I think at that point all businesses and government departments etc have to switch to full on prepare to leave with no deal mode - which in its self will tae so much effort - quote possibly with a general election in the background that it will be really hard if not impossible to stop - unless the EU throw a lifeline of offering to extend A50 - but again elections, quitaly etc Im not sure I see them doing that.
It was always going to be hard to find a deal that united people behind it - but it seems we have found a position that almost nobody supports ...
And this is the main reason why EU members might not agree to an extension, there is still a pretty big uncertainty within the UK regarding what Brexit means and EU members will most likely choose stability over anything else.