You can use just about any type of bike frame to go touring on, but there are pros and cons.
Incidentally, high tensile means the same thing as Cro-Moly. It used to be any touring bike was Cro-Moly, but now you can buy good ones for a low price made of aluminium too.
And for your purposes, the type of bike frame won't mean anything about how long the FRAME lasts. What will wear and break are the components: gears, brakes, rims etc etc. 10,000km might seem like a huge distance to you now, but to a serious road cyclist, they can do 1,000km in a week just training.
In general, the quality of components are matched to the overall quality and price of the bike. Unless you get an amazing deal on a 2nd hand bike, what quality of components do you expect on a $50 bike? But you CAN get good deals on 2nd hand bikes.
And remember the cost of the bike is only a part of the cost of all the other gear:
- racks & panniers?
- helmet, rain gear, shoes?
- camping gear?
- some tools?
One thing that a frame mean't for touring has is places to fasten racks and other stuff on. That's a big help.
And it's not the bike frame, but the whole package that you need to consider:
- gear range (if you will do a to of climbing, or over bad roads, you want lower gears)
- panniers and racks
- size and set-up: drop bars, flat bars, twitchy/road racing handling, or relaxed touring style
It's not really the frame, above a certain quality, the components are more important.
If you buy something with poor components (almost always at a low price overall) then over the next year you will likely end up replacing stuff that wears or doesn't work right. And in the end spend more money, time and hassle.
Below a certain price range, it's had to adjust the components: brakes & gears especially. And they don't STAY adjusted.
Look at a bike mean't for touring with "entry-level" components on: say with ways to fasten racks to the rear frame and front forks. And say with a Shimano 105 or Tiagra group set. Check it out and find out what that tends to cost: both new and in good condition 2nd hand. Use that as a base case. Try riding one, see how easy it is to adjust things. Doesn't matter what the frame is from: anything with Shimano 105 and with touring mounts all be fine.
Then see if it's overkill, or if maybe it's not good enough for you.
Don't get focussed on the money now: rather decide what type of bike you can settle for, and try to get the lowest priced one an still get those things.
In general, below a certain price you don't get something that's going to suit a long trip: unreliable and heavy. Then above that price, to get a slight extra improvement in weight or quality you generally have to pay a LOT more.
But you are unlikely to get the bike for your 10,000km trip and then immediately start on your trip. Rather get something that seems right and do some small trips. As soon as you do your first one you will immediately see what works, or doesn't work, for YOU. And you will see what others are using and get ideas.
Some people are capable of ignoring things on a bike (some noise, something not working right etc etc) that would drive others crazy. How are you? Do you need it to work just right all the time? Or do you have a thick skin?
Some people can either fix things that break, or readily find others to help them. Others will get stuck with the most minor issues and spend days trying to get something fixed.
Google and find sights where people discuss these things. And buy a book about touring: there are dozens out there.