Car audio in the 2000s versus the 2010s differed not too much naman. I think the primary difference is the shift from analog to digital. For example, AudioControl EQX/etc. were very popular back in the 1990s and the 2000s where time alignment was mimic'ed with the usage of independent L/R EQ and balance adjustment to trick the ears. Nowadays it's all digital -- digital crossovers, time alignment, EQ, etc.

However, the proliferation of the internet and sites such as DIYMA has largely moved car audio and acoustic theory forward busting a LOT of myths along the way. For example, a 15" subwoofer isn't necessarily faster than a 10" subwoofer -- reproducing a 40hz wave is exactly as it is: back and forth movement of 40 times a second. What is true is that it won't reach higher octaves as the cone is heavier but it exchanges that with a large surface area to push out the low's with authority.

Kick panels aren't in fashion na either. While they were all the raves before, now it's all about A-pillar installations due to.. well, can't really put up a kick panel if you have a brake pedal there (as in the case of some Hyundai's). They're also a minority too in the United States and people usually do them if they're seeking the pro's of a kick panel install. Otherwise, it's usually the easier A-pillar fabrication.

Acoustics-wise, same lang. People still attempt to throw flashband sa vehicle floor nila as a cheapo DIY deadening after all.

What I believe is the challenge is the integration of head units nowadays with processing units. I also believe the future of car audio isn't 2.1 but rather 5.1. Center speakers practically solves the imaging and staging problems of modern cars. That's why they sound incredible. I'm not even tempted to change the HU of the stock 2015 Everest. Maybe the speakers... but not the HU. The "driver" alignment is time alignment in disguise and it implements it really well.