I think you need to really drill down the problem. Is it the style of your current bags or what they'll be worth in 4 years?
If having a family and buying a house is relatively new territory for you, you may be having a bit of an identity crisis. I don't say this in judgement, just that big life changes can cause us to redefine who we are and then, what we wear/how we present ourselves to the world.
I think your current bags are pretty classic. At the very least, they are understated and therefore not trendy. I doubt anyone will be looking at you wearing them and thinking how horribly out of date you are (and if they are, they really need to examine their own priorities!).
If the bags just don't feel like "you" anymore, and you no longer want to carry them, then sell and buy something that is a better fit. But if you are worried about finances, hang on to what you have -- they are lovely bags -- and start a rainy day fund for a new bag to buy "someday." But worrying about what will be in style in 4 years is a waste of time, imho. There are lots of trendy Chanels out there that will look dated in 4 years. Plus, who knows what your bag needs will be in that time?
If you want to be totally safe, save up for one of the ultimate classics (Hermes Birkin or Kelly, Chanel classic flap,
Gucci hobo, Louis Vuitton Speedy, etc.) But be sure the style works for you. Those bags don't always recoup full value either depending on the condition of the bag and the saturation of the market.
At the end of the day, I guess my advice would be to keep what you have and really look at what works for you. If you're in transition in your life, don't make any big (expensive) or irreversible (selling a discontinued bag that you won't be able to get back) handbag decisions until you are through the transition and in a more stable place. HTH.