Hi,
Has the night train between Milan and Paris been cancelled?
Yes, a few years ago now. Sad news on paper, but it was not very reliable, the rolling stock was really ancient and in questionable condition, and it arrived in Milan at like 5.30 AM from Paris so not a huge loss IMO.
Is the high speed train routes a better option then the Airplane of is a mixed pro/con kind of thing.
The train takes 7.5 hours or so: it is about 3 hours slower than if you fly from Linate to Orly (the recommended option): for many people, the time saving is worth the hassle. However, the train times are convenient: you can leave Milan in the early afternoon and reach Paris in the evening, so you do not lose a whole day. Scenery is "meh", despite crossing the Alps - to make it better you can travel via Switzerland but it is more expensive and usually takes 30-60 minutes longer, with a change of trains. A window seat from an airplane will give you great views of the Alps on a clear day.
The main argument in favour of the train is the lower carbon footprint at no extra cost and with a reasonable time penalty.