Given that Sheffield City Airport was built shortly after the Supertram was completed were there every any plans to expand the Supertram there? I wouldn't be surprised if there were.
No there wasn't - the airport came about as a bit of a whim of the Sheffield Development Corporation in the early 90's to sex up the otherwise drab brownfield site for developers.
There was an aspiration to take a tram route up to Wickersley, I don't think that funding was ever secured for it, not a route finalised, but the residents along the A631 were up in arms about the idea - I can't for the life of me recall when this was - late 90's probably.
Back "in the day", planning and funding processes were very long, the trams had been shut down by the 1960's and were seen as a second rate means of getting people around - to be fair, in the UK they were old tech, effectively a bus on rails, which offered limited route flexibility and the trackbed would have been poor by today's standards. I'm too young to have any first hand experience. Sheffield originally had plans for an urban motorway (search "Sheffield Urban Motorway") in the late 1960's when the city was its own entity within West Riding. By 1974, South Yorkshire County had taken charge of planning and highways, the oil crisis had hit, the politics were very left wing and the urban motorway was canned in favour of a people mover much like Heathrow T5 - this kinda evolved into a modern tramway and by 1986 a route was fixed and laid before parliament.
I'm not familiar with the Manchester or Leeds proposal history timeline, but the race was on to get the first modern tramway operational in the UK, Manchester bypassed the planning nightmare that Sheffield had by using old railway lines - effectively a tram-train that didn't mix with trains and in doing so won the race by a few months. I've often thought that without the mix of oil crisis, left wing politics in South Yorkshire and the in fighting between Sheffield and the county (Barnsley) the modern tramway wouldn't exist in its current form, with tram-train style systems like Manchester, Newcastle and the class 14x winning through.