I'd say it's more competitive than ever by numbers and depth, but maybe not by percentage of the population. We have the highest populations ever in history right now by a lot. So a 10% decrease in 'serious' runners by population can still yield a larger number of 'serious' runners therefore improving the depth of competitive athletes and having more guys faster than previously considered elite levels.
For example, the number of guys in the world that run under 13:20 for 5k now is WAAAAAAY more than the number of guys that could do it 30-40 years ago. In the 1970's just a handful of guys could run under 13:15-13:20 range, now we had like 5-10 guys do that at Payton Jordan last weekend. And same for marathon, we now have over a hundred guys running under 2:10 in the marathon, go back 20 years and we had like 20 guys that could do that in the world.
Even in the NCAA, look at the 5k indoor this year. The cutoff was 13:41 to go to the NCAA championships, go back 10 years ago and the cutoff is typically around 13:50. Go back 20 years ago and you just have to go under 14 minutes and you've got a shot.
Sure, most normal people don't know the world record holders, but do you know the world record holder for the 100 meter backstroke in swimming? I don't. Who scored the most goals in the Premier League this year? I have no idea. Who won all of the Grand Slam tennis tournaments this year? I have no idea. Who won the Tour de France last year? I have no idea.
Running is still just a second or third tier sport, but the number of super serious fans has never been higher than now, but the percentage of the population that is a super serious fan is still very low.