With a vehicle of this mileage, unless you personally have a fair amount of experience with the mechanics of automobiles, you definitely should take it to a qualified, ideally trusted, mechanic to give it a thorough inspection. It's not all about the engine - it's also about the differential, transmission, bushings, bearings, struts, brakes, ball joints, etc.
The area of the country can make a big difference as well. For example, a vehicle this old with high mileage where I live (San Diego) can still appear new underneath due to no rust (like my 2014) but a vehicle in the northeast can be a wreck underneath from the rust and deterioration and pretty much ready for the scrapyard despite the engine still running okay.
I put 235K on my last vehicle and that was a Dodge Durango. At the time I donated it, it was still doing fine on the original engine and trans and really had few things go wrong with it. I hope an MDX would do at least as well as that. So far my 2014 MDX with 86K miles has had nothing go wrong with it.
So, it's possible the 2015 with 160K miles is good for another 100K miles but you need to be realistic and perform the mechanical checks I mentioned - really inspecting it from underneath and knowing what to look for - i.e. having it done by a good mechanic. You also need to be realistic and know that most likely 'some' things will fail in the next 100K miles and have some budget set aside to handle it - joints, bearings, bushings, struts, etc. I'm not saying all of those will need service but most likely some will.
You could also consider a different 3 row used vehicle that sells at a lower price point than an MDX where you can get a lower mileage vehicle for the same cost - maybe a Pilot, Highlander, etc.