Would there be any chance for high speed classic compatible trains for instance to join here from Leicester and then continue north towards Leeds and maybe Glasgow for instance?
Yep, now we know where the stations are, so the location and layout of junctions is the next fun area of speculation.
The south side of Toton is heavily built up (Sawley / Long Eaton), but the 2 double track lines into Toton are under utilised. I would assume that one of the existing trackbeds will get a wider curve for HS2 and Trent Junction will be remodelled so freight & diversions can all use the other approach.
Given that HS2 will need to pass through/over Trent Junction, that would be a potential junction on HS2, however there isn't unlimited space at Trent Jn, you have housing to the North, Trent Lock to the south West. It's also in the Trent flood plain, so anything new will be viaducts rather than tunnels, so noise levels become an issue for nearby housing.
I would expect to see a new Chord on the classic lines just north of the new 'Toton International' so some local trains from Derby/Leicester could approach from the south via Trent Junction then continue into Nottingham (through Wollaton/Lenton) without reversing. That might be unpopular with some as it would miss out Beeston, but then half the eastbound XC BHM-NOT services miss out Beeston anyway. On the + side it would ease congestion /create diversionary route on the western approach to Nottingham. A new local station in the Wollaton area would also be a possibility, but I'm really getting into fantasy land now..
As we discussed before, there are plans for housing between Toton Yard and the new NET park & ride currently under construction on the A52. These plans include an undeveloped corridor for future NET extension. The layout of the P&R has also kept the land beyond the terminus relatively clear. It will be interesting to see if the NET is just extended to Toton or beyond towards Sawley or Sandiacre... Long Eaton & Stapleford town centres would clearly be popular places for tram stops & could do with some regeneration.