Hi Maanv, thanks for your kind words!
Whilst I personally bought a 16GB MacBook Air with longevity in mind, I think the 8GB model is still a fantastic buy. Apple wouldn't make an 8GB model if they didn't think it would work for most people, long term.
As you'd expect from Apple, they've polished the user experience to ensure that when your computer needs more memory, it's able to temporarily use the SSD to fill in the gaps. The SSDs in these computers are so fast that it's a near-seamless experience.
While getting the 16GB model would be advised for longevity, and give you the most flexibility to do what you want with your computer in the future, Apple's designed the 8GB computers to work flawlessly for most day-to-day tasks, and provided a seamless provision to compensate when you're really pushing the boundaries of the memory.
You may experience some slow down when really pushing the limits of your computer, but for daily use, you'll have no trouble at all!