No - some journeys won't be made. Some will be made by bus.
Hardly any will be made by bus. The bus is usually a choice made out of desperation.
If you don't have a car and you want to go to London for the day and decide the train fare is too much, you might go by coach, you might not bother, you might go somewhere else. It's not as binary as you make it out to be.
Almost everyone has access to a car. The journeys will be made by car 95% of the time. Those that don't will have to take taxis because most buses aren't profitable. If we're insisting on public transport being 100% profitable it mostly won't exist, except in large cities.
But costs *can* be controlled - the biggest cost on the rail network is going to be staffing - so another look at OMO, running 2 tph rather than 3 or 4 reduces the number of crew needed, reducing ticket offices (which is being looked at and TFL have already done this on the Underground), not running the "once a day" extension to some random destination (again some of these have been done e.g. EMR running to Leeds - others which could be looked at include LNER running north of Edinburgh for example), reduce the number of "duplicate" services, reduce on-board catering where it is little used - the list goes on.
So service cuts rather than outright closure. But then it becomes even less useful, so less people use it, so less financially viable etc.
Try making staff redundant the unions kick off, strikes etc. no service, lose even more passengers who start using cars and don't come back.
All of this stufff is just Beeching again, didn't work, won't work now.
Turning it the other way, what would be the effect of a 10% rise on all ticket prices ?
If, for example it led to a 2% drop in use but an 8% increase in revenue, that would actually improve the railway network's financial position.
Prices are already ridiculous, why 2%?
Reading some of the posts on here the idea of a "social" railway for the benefit of all with costs and profits and losses spread across the network has clearly disappeared. Many of the comments are pure outdated neoliberal dogma- if it's not being used by many cut it to the bone or shut it. And if that means you can't travel at all - then stay at home.
My argument is the railway will never be profitable, but if we're going to have it it needs to be accessible and useful which means subsidised and not having stupidly high fares.
If making it profitable is the aim you might as well shut it down tomorrow, it will never happen.