The old rail line won't reopen. The station building is now a b&b and the track is now a cycle path.
The old line runs too close to the existing line for there to be any point. The current heritage line that could be extended back to Alton station is hoped to one day connect to Stoke and the mainline, but there's already the Uttoxeter service from there. The old line has been cut off at Denstone by housing developments so unless Alton became the end of the line it would take considerable effort to reroute to either side of Uttoxeter. Alton station would still require a shuttle bus unless a second (third?) entrance was built.
Maybe if the heritage line took back Alton station it'd be a nice alternative but as a major route to Towers, never. Coordinated, practical buses Uttoxeter, as well as stations that are on the mainlines like, Stoke, Stafford, Derby, East Midlands Parkway are the simplest solution.
The problem is there would be a lot of empty buses outside of peak hours and times. The move to online ticket sales would help planning; give an option to say where you want picking up and when. Again Towers needs to become year round, because whoever is responsible for the services, what do they do with the extra fleet and staff when not needed?
Towers could subsidise travel or bump up the entrance fee to include 'free' travel. Not necessarily to the point of them making a loss but I'd imagine if it became a popular way to travel to the resort, car park space could be expanded onto and the initial loss considered an investment that frees up space for more lucrative use.
Perhaps if the bypass is ever built it could be restricted to buses and coaches, at least during the morning and evening rush.