I'd be 99% certain those are for their current (expanded) services - if/when they get Liverpool-Nottingham, some degree of staff from EMR will be TUPE'd over along with it, surely - I certainly don't think there's enough expansion in EMR's regional routes that they can all be redeployed.
TUPE from EMR to TPE is likely to be on offer if the route changes hands, but it's too early for anyone to get more specific. TPE must plan some way ahead to meet driver shortages and 18 months from recruitment advertising to driving trains isn't very long, especially if significant numbers may be required.
If EMR keep the route any TPE driver recruitment contingency planning won't be necessary. If they don't it is.
Some EMR crews would probably be offered redeployment within the company and accept. How many offered and how many accepting EMR redeployment is largely out of TPE's control, but not totally. A few may decide to leave the company (and the industry) depending on any terms that may be made available and their personal situation. Voluntary redundancy or early retirement packages might be an option.
It is by no means certain that all would carry on as now, just wearing new uniforms and trained for new traction. When the time comes TPE could offer enhanced terms to those being TUPE'd over. That could be a range of features tailored to how many were needed be it short, medium or long term. There are big savings on training to employ already trained staff - and the same applies to EMR wanting to retain skilled people.
Having different terms for different groups of employees makes operations more complicated. As a TPE manager I sense I'd rather avoid that and employ as many as possible on standard freshly recruited TPE terms. I'd want to have an available pool of my own trained people ready to take on a new route. Short and long term costs and benefits may conflict.
But I know nothing about this case, just adding 2+2 to make 5 or 6! And TUPE is a digression too far. It's a complicated and emotive subject - been there, got the T shirt!