Keep the Tahoe. Your worries of the unknown future are illogical. Who knows what tomorrow will bring. These vehicles are great and last a very long time if you maintain them. That’s the reason you can get such a great trade in value on it!
Also, have you been following Ford? They could be headed towards bankruptcy or at the very least significant financial distress. I wouldn’t buy anything from them right now till they figure out what they want to do going forward. (They should probably stop producing all vehicles except the Mustang and F150, but who knows).
Keep the Tahoe, maintain it, and if in the future you get the itch to buy something new, talk the wife into letting you make your own decisions on what truck to drive! (In a nice voice, lol).
Of all posts, this to me makes the most sense. You don't know of any problems as of yet, and everything has worked out OK so far. So why would you decide now that your Tahoe won't keep working OK for your future ? Right now you have the towing ability you need, and with a V8. Do you think with a Turbocharged V6 it will stay that way ? Ford doesn't put a V8 in the SUV lineup, so you are talking about getting a pickup, which if you decide on carrying people besides the boat, your going to have to get a Crew Cab pickup. That means getting a larger truck than you now have, why ? Grat you I have had my Tahoe for two years now, (It was a lease and a rental before I got it and with 62872 miles on it it is still very comfortable and reliable truck. Could I trade it in. . . Sure, for what ? You NEVER are given as much as you think when you trade in anything ! this has been proven many times over by marketplace investigations ! A dealership NEVER loses a penny, Trust me I know !
Stepping up lot of times is stepping back. I'm sure that a V6 turbocharged engine is fine, but why ? If you tow a lot and a V6 is going to be pushed harder with the current load, or harder than your present 5.3 V8, then a V6 it's going to develop problems (sorry Ford guys), but it's simple mechanical logic that a V8 naturally aspirated engine isn't pushed as hard than a V6. More moving parts = more things to wear out. I'm not saying this because I own a V8 Tahoe, it's only recall was a ECM reflash. But look at the Tahoe, if it were or was a problem vehicle, why would police departments across the country use it ? I know that a ford explorer are used quite often , but what is their pursuit vehicles ? Tahoes.
If you are worried about problem in the future, wait till they actually develop, then think about jumping ship. I really think that the problems to worry about aren't anywhere in sight yet. If you worry about transmission problems, put on a larger trans cooler. If you think there are lots of other problems, where are the statistics ? We have Tahoes here that are pussing 350.000 miles and still sounding like new. You can do whatever you like, but running because the sky is falling guess what, it Ain't ! Good luck and calm down. just enjoy the present day, that is where you live.