I personally think the 4L market is an affect of the Chinese economy, stemming from the quest for people to find a safe haven for investments.
As of right now, these domains are being looked at as 'safe haven' investments, and I have seen a lot of safe haven investments go sideways very quickly - especially when they are "NEW" and "DIGITAL". (Bitcoin)
I got out a few months ago, mostly because I bought my PinYin 4L's for $20-$40 - so I'm fine with the ROI.
Over the next few years I think PinYin 4L.coms will mirror the performance of BitCoin, in that there will be a great rise and then a steep fall back to normalcy. Where that rise and normalcy will end up, I cannot say. It may fall back to the 'going rate' for random 4L's or it may fall back to the current market price as it stands.
But I think that of domains in general over the next 5-6 years.
In a few years there will be this great explosion of domaining, and the prices will reflect the demand. Part of the explosion will be forced by the powers that own top-tier names, and part of it will come from the general public becoming more tech savvy and the mainstream media dropping the 'squatter' narrative.
You can already start to see the framework this being laid in articles by top news sources today.
After that, the domain market will be in a state of disarray, will likely drop significantly in value, and then will recover a number of years later.
Nobody likes to hear that, but it's 'the pattern' that all things in this world follow.
No worries, we've all got good times ahead for quite some time.