Is there going to be a North Wales route from euston station in train sim world 2 on PS4 and euston station is a main line
Not a chance, Crewe to Holyhead would be about as long a route as you'll get for TSW2. From Euston you'll probably get to Milton Keynes.
Euston Station is an entire mainline? Snap, that's awesome! I take it there's about 8 trains per hour along it, between platform 3 & 8? Seriously, the best you'll get from North Wales Coastal is Crewe - Llandudno or Chester - Bangor. Not a chance will you see the entire thing to Euston in one go. Also, it really kinda frustrates me when people suggest a route "For PS4", "For PS5" as if they expect it to become an exclusive - save the effort, every new DLC is on every platform.