Aside from the Gorge it seems feasible but I second the vote that you are trying to do too much in too short of a time.
Keep in mind there is travel time, finding of hotels and the need for food and rest. And to really experience France food should be given more time than you're used to and rural, quaint areas take some time to appreciate.
If you take the advice to drop Cassis and the Gorge you pick up two days. Paris really deserves another day make take two days in Nice and add Antibes or some other Riviera location I think you're closer to realistic. Keep in mind it will take you 6 hours to get from Colmar to Avignon so day 6 is going to be almost entirely swallowed by travel.
Using your itinerary as a starting point:
DAY 1: Paris: Arrive, rest (depending on time of arrival you might wander Luxembourg Gardens or something low key)
DAY 2: Paris: Full day
DAY 3: Paris: Full day
DAY 4: Paris: Day trip to Loire Valley - castle/wine tour
DAY 5: (2.5 hours train) Alsace - travel/stay in Colmar
DAY 6: Alsace- visit Kaysersberg or Eguisheim
DAY 7: [6 hour train trip] Provence - Avignon see city in the afternoon/evening
DAY 8: Provence - Arles (20 minutes back to Avignon on the train), maybe another town or site?
DAY 9: Provence: St Remy, L'Isle-sur-la-Sorgue, Nimes - Market/Cooking Class?
DAY 10: [3+ hour train trip] Nice
DAY 11: Nice/Antibes/St Paul Vence/Villefranche-sur-Mer to your taste
(You could leave Provence in the evening of Day 9 and get a full day in Nice on 10 as well.)
Market days in Provence vary in each city by day. Figure out where the best ones are on day 8 and 9 and plan accordingly. St Remy, Arles have good markets and the one on L'Isle-sur-la-Sorgue is famous. Markets usually run from early morning and start to wrap up after noon so it is a half-day activity.
If you provide a better idea of what your mine interests are - food, wine, ruins, museums, art - more concrete suggestions will probably be forthcoming. Bigger cities or tiny towns? French Riviera has Picasso and many other modern artists while Arles and St Remy are popular with van Gogh fans.
Sounds like you're on the right track, hope that helps,
=Tod