Right
For it to provide jobs, it would have to create more demand than there is currently, whilst having more capacity than there is currently, thereby increasing the amount of trade via rail by more than the volume of freight switching from road. Whether or not it does that is not for me to say, and nobody here could answer without a study to determine the answer.
Will Network Rail spend the money? Unlikely without the aforementioned study.
Will it happen? No.
1. It's a lot of new infrastructure required in an area in which land is relatively expensive and new infrastructure is difficult to build.
2. You'd have to have the capacity there on the Altrincham route, which there isn't without redoubling, and although that is probably needed anyway, there isn't the money to do so.
3. If you were going to build new infrastructure, you'd do it directly from the WCML to the CLC, which would be a shorter distance of new route required, further outside Manchester where land is cheaper, and even then, there are far more valuable interventions elsewhere with the limited budget available.
Overall, this is a worthwhile scheme, but it's not the best solution to this problem, and it's not the most pressing problem around.