I hope canning in Cottage Living is at least at the level of the Sims 3 Store Canning station and its products. In the Sims 1, there was a canning station but it was very basic. Using it produced a crate of 6 jam jars which your sim could sell immediately or give away as a gift (which did have the advantage of providing a healthy relationship boost in a game where it was notoriously hard to maintain relationships).
In the Sims 3, your sims could either can, preserve or pickle most produce in the game except for the life fruit and flame fruit (I assume because of their special properties). The resulting jars were each distinctive both in the interior of what you could see through the glass, and with a unique label/name. Most of the berries and fruits made jams, but tomatoes uniquely produced ketchup; oranges, lemons and limes produced marmalade; cucumbers could be made into either pickles or relish; eggs could be pickled; cocoa beans made chocolate spread. The jams could be spread on either toast or scones for "smothered toast" or "smothered scone" as a dish to be eaten. Unfortunately you couldn't sell any jams or preserves at the consignment store or through the bakery, but only directly from the sims inventory or the station.
I don't like when the developers take away a functionality that previously existed in an earlier game, so I hope that we can at least do all of that in Cottage Living, and hopefully more. Ideally I would like to have a host of unique jams and spreads (for every harvestable and for combinations of harvestables -- which you couldn't do in the Sims 3), with their own proper names and appearances, as well as the ability to spread jam or preserves on any bread, scone, or baked pastry in the game. It would also be nice if sims could take preserves with them tomb-exploring and adventuring in Jungle Adventure and eat them directly from the jar without any fear of them spoiling (because that desiccated grilled cheese has always looked so disgusting to me).
It would be even better if jams or preserves could also be ingredients in certain dishes, like varieties of jam being used in jam tarts or pies, or ketchup being added to fish and chips or hotdogs and hamburgers, etc. It would also be nice if there were a few new recipes that you could only make if you had jam or preserves in your sim's inventory such as jam-filled puff pastries, victoria sandwiches, cobblers, crostadas, black forest cake, etc. (We're only getting a few new English-style recipes like beef wellington so I rather doubt that there will be many new options for canned goods to serve as ingredients in new recipes, sadly). It would also be nice to be able to sell jams and preserves on Plopsy and through the sale table, as well as at the new grocery stall in the new town square.
I expect I will be disappointed in the amount of new foods we will get from canning, and we will only get jam on toast, and if we are lucky, on scones, but I am still glad that canning is coming back to the Sims 4 at last.