Not even chanel or hermes bags are "investment" pieces. You will never sell it for the amount you bought it or even more because it's a bag. You use it. Like a car, it loses value the minute you leave the store with it.
Investment pieces are houses in upcoming trendy neighborhoods, stocks, ect. Not bags.
I think the Dionysus is a classic piece. Totes will always be in, it fits a LOT, the print and color scheme isn't busy (if you buy the regular non bedazzled one), it matches with everything, it's a nice looking bag. I don't think structured totes will ever go out of style. I think the GG print will make for a great vintage bag in the future as well. Dior is even reintroducing the label canvas on all their bags. It's super trendy now. I think the Dionysus will stay trendy and will also be seen as a classic piece.
Gucci is going hard with the Dionysus line and I don't see them going away with it. It'll be like the soho disco bag I believe. Always "in" and always around in stores.
You should buy bags that you can see yourself using years down the line and not for trendy reasons. If you need a tote bag that can easily go from day time to night time transitions, get it.
Don't ever buy bags with the intention of selling them later. Trends come and go, buy what you love.
I literally have a $200 basic camera bag from popandsuki with my name on it and it's not sellable or an investment piece but it's so so cute and small, serves my needs, it's $200 I won't get back but I use it almost every day. Worth it. My cheapest nondesigner bag in my collection and also my favorite.