I think the kind of prices you have mentioned are unrealistic expectations in my opinion. It took 15 years (approx) for llll to sell out, it would thefefore be unreasonable to think they will suddenly become very valuable quickly.
Now having said this, it is interesting to note that China is becoming a large internet using country, and many poor letter combinations appear good for them. I have several rubbish llll.com that get traffic from (same llll.cn) Chinese sites.
If llll.com remain unavailabe, and are not dumped back on the market at reg fee, then long term, you would have to consider prices to rise. Many things could, or will affect this happening, such as increased extensions, and the continued effect of the softening world economy, to name only two. Many premium llll.com continue to rise as we speak, such as quad premium cvcv for example, and other premium combinations.
Like any investment, there is always a risk, so as a buyer you have to judge whether investing in llll.com is currently worth the risk or not, many say yes, many say no. You have to decide for yourself in the end. It is always good to diversify any investment/s you make, to reduce the risk of being over exposed in any one sector, such as llll.com, that is what i would currently suggest.
I still believe, that long term prices are up, but long term is more than two years in my opinion. My prediction is that prices will rise slowly over this time period (long term). At present, prices still look like falling further (short term).