Yes, definitely keep that Vitamix. Never have I ever regretted buying mine. It's an investment that delivers.
Soon to be mom of 4 kids here, and I do have both an Instant Pot and an Air Fryer.
As between the Instant Pot and Air Fryer, I'd say it depends on what you eat, how many people you feed, etc. Do you cook larger (1lb plus) pieces of meat or poultry often? Do you find yourself with dinner being an hour away and "oh dang I forgot to put the pot roast in the oven?" Or do you want to cook dried beans quickly? Then you want an IP. If you hate making rice on the stove or boiling eggs on the stove, then you want an IP. (Some say that IP boiled eggs are easier to peel than traditional stovetop boiled eggs but I'm not sure I agree.) If you want to slow cook but don't want to buy a Crock Pot or don't want to use a Dutch Oven, then you want an IP. You can also steam in an IP.
So yes, the IP does a TON and some people find it convenient. However, I actually would get an Air Fryer if I had to choose between an IP and Air Fryer. Why? Because, with the exception of fast pressure cooking, I already have the pots/pans/Crock Pot that can perform the additional functions of an IP beyond pressure cooking. For me, it's been a redundant appliance. Plus I'm a meal planner so I never end up in a "oh dang, I forgot to start the roast" and need the pressure cooker situation.
The Air Fryer prepares food in a way that I've not been able to replicate with any other appliance. The oven, even a convection oven, has yet to give me the same results. Like Trader Joe's frozen cauliflower gnocchi, amazing in the Air Fryer! Basically all vegetables are roasted ("fried") to perfection in the Air Fryer. Hamburgers, salmon, chicken nuggets or pizza (mom of young kids, here!). Amazing in the Air Fryer. The list goes on, but again for me it comes down to not being able to achieve that taste or texture with any other kitchen instrument.
But regardless you're in a win-win situation here, so enjoy whatever you decide!