Everyone is waiting on Theresa May before choosing their side of the room
The BBC and The Telegraph are all reporting that ERG MPs will only be backing the Brady Amendment as long as May commits that she will explore the recently emerged Brexit 'Plan C' i.e. The Malthouse Compromise. In an astonishing turn of events, Jacob Rees-Mogg has joined forces with Tory remainers in support of a plan to replace the current backstop (which would be acceptably indefinite) and also extend the transition period to December 2021.
But the reports are suggesting that they will wait on what May has to say later in the day in parliament before committing to anything. As it stands, there's also no firm word on where the support by the DUP and Labour front benchers currently lie so I reckon a lot will depend on what stance May chooses later (although we sort of have an indication as noted here).
Either way, when push comes to shove, calls for an alternative backstop whether or not be it via the Brady Amendment or the Mogg-Morgan 'Plan C' will surely be shot down by the European Union at the end of the day.
Hence, after all the debacle here, sure the UK parliament is at least helping to minimise the risk of a no-deal Brexit taking place but we're no closer to getting a Brexit deal between the UK and the EU now as we were in December last year.