Its possible though, Northern management could easily decide that they no longer reconise the RMT as a union but as a band of troublemakers hell bent on damaging the rail industry as a whole.
Northern could contact SWR (who are also having strike action) and declare to them that the RMT is no longer a union, then all the other TOC's take note and slowly but surely the RMT is finished and all over which member of staff does the doors at Northern.
I can see it happening.
I can imagine seeing the next Northern franchise being fully DOO and staffed by non unionised employees, all because of the RMT's actions during this franchise.
Whilst it's possible I can't see it happening - yet! The usual course is for another union to recruit members and arrange to be recognised to act for them. The employer then withdraws recognition of the first union and agrees a deal. However that requires a large number of employees to change allegiance. Unionised work forces are usually very reluctant to give up the protection of a union altogether - and in the railway industry I don't blame them.
The most famous example is probably the UDM in the Nottinghamshire coalfield when working miners left the NUM. In another industry the union I was involved with became too militant for the main employer and is no longer recognised, two more compliant unions having split representation for a lower number of employees.
Seeing the pickets at the gate on Saturday, and the lack of trains on my line, I can't see this ending soon. However, a few right or wrong words can make a lot of difference, said on either or both sides! So far it's getting like the Western Front 1914-18 and the public doesn't see the need for it.
Please can those on all 3 sides (TOC, RMT, DfT) get their heads together so those of us on the 4th side (the poor souls wanting to use the trains) can start to rely on them 24/7 once again?
Of course the employer could take a nuclear option by saying they were totally closing the franchise down from 1st January until a deal is agreed for normal working. Possibly reopened line by line as workers agreed terms on that basis, maybe moving lines between depots to achieve that.
Or even worse, handing back the franchise so the RMT had to have another ballot for action against the new TOC. These are unlikely scenarios, but once the cats and the pigeons get really mixed up anything can happen, and all are likely to lose.