My brand new laptop has a french keyboard, but I've connected to it an full size dutch keyboard. Linux is great because it can actually deal with such weird setup so that for both keyboards when you press a key you get what you would expect. To do that, I configured the french layout as the default (because it's always connected to the laptop!) and whenever I plug the dutch keyboard I've got a little script which does this:
xinput --list # to find the id of the keyboard
setxkbmap -device $kb-id nl
Now, all this troubles could be avoided if not every country had a different keyboard layout (Switzerland is special, they have several layouts). 100 years ago, this could make sense, but now that there is so much exchange between countries, this is bringing more pain than advantages. One solution would be to simply change the spelling of every language to restrain them to the good old 26 basic letters, and be happy with a US layout forever after. This could happen, the Turkish people did manage, but for sure not any time soon, and anyway the culture should not be driven by the technology. It's up to the technology to adapt.
So what I'd really like to see is a generic keyboard layout, which allows to type any latin character-based language (or at least all the official ones present in Europe). The us-international layout is not so bad, but they are lots of small adaptations needed to not make it a pain to use (especially on windows where by default the diacritics are added to the next letter). Some European peoples are at it, and I hope it goes somewhere. While at changing the layout, we could move to dvorak, so the loss of direct access for the special keys of a language would be more or less counter-balance by the increase speed provided by the dovrak layout.
Even more useful would be to have the input method follow more closely the normal behaviour of putting diacritics: you first put and the letter and then you put the diacritics. It would in addition allow to add easily diacritics while reviewing a text (put the cursor just after the letter, and press the diacritic you want to add). Today, in Xorg, a first layout providing such a mechanism appeared: "USA - International (AltGr Unicode combining)". As its name implies it uses some special features of unicode. This has the disadvantage of not yet being correctly supported in every program, but that's the way to go!
Test this new layout, and report bugs on application not correctly responding to it, and propose better versions of the layout :-)