If this is proven then would not the client be also entitled to a percentage of the profit. I think it would turn some attorneys to drafting proceedings so that they could be profitable secondary to what might be for the good of the client. This could be a real possibility in that an attorney may be able to $500 an hour for their work and then being able to profit on what has already been paid. If there is a profit motive outside of the client then it is likely the motivation would not be just the client but the broader market.
It is a slippery slope, we are not talking about music or movies here. Most people sometime in their live need legal professionals and they should not be represented based on broader market.