This will be an ongoing battle. What to take? Buy there or ship? Nothing is perfect. If you are not starting out with a solid plan, it is even harder. I currently have a 2011 Triumph Tiger 800XC. A good choice for a world tour. Not great, as dealerships are few and far between in some areas, but the world is much smaller these days so a good choice. Except this one has over 70,000 miles on it. More by next year. And it will have experienced 7 New Hampshire winters. There is a lot of rust under the "hood". With this many hard miles, the bike could not be sold for much. The question then becomes, do I take a high mileage bike, and just dump it if something expensive fails, or do I sell it for practically nothing and buy something expensive, that I will be willing to spend a lot of money to fix? A weird problem.
I have a 2004 Honda ST1300. This is considered a Sport Touring bike. Emphasis on Touring. This is a big bike. Granted, the big girl can dance and dance well. A ton of fun in the twisties, and comfortable on the highway, but still not a great bike for a world tour. Now, for a European Vacation, not bad. A bit big, but not too big. Certainly an option. The bike will have over 100,000 miles by the big date, but this bike can routinely get a quarter of a million miles. All the typical weak point failures that occur near 100k miles have been repaired. This would not be a bad choice if I was staying in more civilized roads. It is not bad on dirt roads, but really not the first choice. Or the second. Or..... anyway, not an impossible bike to bring, but I need further thought.
So, it is probably not a good idea to bring what I have. Getting these bikes to Europe is easy, and not all that expensive, by flying through Canada. Air Canada has an offer every summer where you put your bike on a plane, you get on the plane, and you are reaquainted with each other in Ireland. A definite possibility, but the choice of bike is still in question.
One of the bikes that I think would suit me is the Yamaha Tenere. This is a big dual sport/enduro bike. But it is reliable, comfortable, has tubeless tires, shaft drive and plenty of accessories available. Another choice is the Kawasaki KLR 650. A smaller and much cheaper dual sport. I have much of what is needed to make it a world touring bike. These are not the best bikes. They are not the best at anything, but they are pretty good at everything. A lot of people use them for world tours. Stone knife simple for the most part. Cheap enough to abandon if necessary. Not a bad choice, especially if you are looking to keep cost down. But cost is not the major driver here. Sure, it is a concern, but overall trip satisfaction is much more important.
One good option would be to buy a bike in each region, then sell it before I leave the area. This can be complicated, but it saves on the expense and complications of shipping.
This subject will be addressed repeatedly until a final choice is made.