Brainstorming cases are some of my favorite, both as an interviewee and an interviewer. They're a fantastic way to quickly and effectively get to how a candidate thinks, and to show off your thinking to your target firm.
The trick to realize with cases in general, and these cases in particular, is that -- spoilers -- THERE IS NO FRAMEWORK.
Did James Casey go through a framework when he founded the progenitor of UPS in 1909? Nope.
So hopefully, the lack of a 'right answer' here can help de-stress the process for you. In the absence of a 'right' answer, we're only left with good ones. So what are some good ways to think about bucketing future trends in the european logistics sector?
One particularly simplistic way is to break out an issue tree of 'revenue driving trends' and 'cost driving trends.' On the top half you'd put things like e-commerce, greater vertical disintigration in industries (leading to more shipping from supplier to customer), and greater tarrifs (driving down business). On the bottom half you could put things like fuel costs, capital costs of aging equipment, pension costs, or impacts from technology (e.g., blockchain, driverless cars).
That's a pretty solid answer, especially if you do it quickly and acknowledge up front that you know nothing about european logistics. At that juncture you ask for any trends the interviewer has heard about besides the ones you highlighted, and off to the races you go.
If you want a tad more flash, you could borrow a structure from sociology/history and apply some variant of the PEST framework (https://en.wikipedia.org/wiki/PEST_analysis), one version of which might be familiar to you from 'social studies' in elementary school. If you were to break thing sup to political, economic, sociological, and technical trends, you could then identify which ones impact revenue and which ones impact cost.
Yet another way to do it, with an investing flavor, is to use the 'headwinds' and 'tailwinds' division. Tailwinds example being trade wars, headwinds example being e-commerce.
As this hopefully demonstrates, you really can't go wrong with which framework you choose -- you just need a way to divide the world, and let your creative juices fly in populating the category. The choice of framework should be somewhat tailored to the interviewer and the impression you want to give, for bonus points, but that's a top 1% move that frankly isn't absolutely required to 'pass' the case.