That would solve some problems but create others. If it's "original inventor" rather than "original inventor and heirs" you've just created an incentive to assassinate inventors (and a disincentive to invent if you're getting old).
Even if it's "original inventor and heirs", you've created a liquidity process -- if you're a chemist with lung cancer, it would be great if you could sell your novel synthesis in order to pay for your cancer treatments rather than needing to start selling drugs yourself.
And then there's the problem of defining what a "practicing" entity is, of course. Someone who has at least one customer? Someone who has used the invention themselves? Someone who was planning on building a product, but didn't get into YC and ended up working at Microsoft instead while he tries to license his invention to raise money to pay for his next startup idea?
I don't follow the chemist example. The patent is still valuable to companies who do want to productize it, or even companies that don't. Companies can still buy and hold patents without doing anything with them, it's just that they are barred from litigating them. They can still resell the patent to someone else, potentially for a profit.
A "practicing" entity has either brought a product to market, or uses the invention themselves in the process of building a product on the market. Someone who is planning on building a product but has no funds doesn't get to litigate unless they are the original inventor. Your last example seems to imply that they are the original inventor.
I think trying to come up with too many special cases is just the wrong approach. Patents are intended to be somewhat property-like, and transferability seems like a completely reasonable thing to me. In fact, it would be quite challenging to prevent transferability without impacting a lot of contracts -- they'd just set up some power of attorney scheme to make it seem like the inventor is a party to the lawsuit.
The root of the problem is more closely related to the imbalance of power in a lawsuit: one party has the ability to subject another to great cost; with little or no cost to themselves, even if they are completely wrong. That imbalance is what makes extortion possible, and this bill seems to be more directly aimed at that problem.
To force the plaintiff to take on more responsibility, perhaps they could go further and require posting a bond for the cost of the trial in case they are wrong. That would prevent them from just setting up shell companies and then saying they can't pay when they lose. The judge can be involved in setting the bond amount, which should help sort out the rest of the problems and keep the incentives reasonable.
The chemist doesn't want to spend time going around to companies trying to license his technology, and he certainly doesn't want to spend years in litigation. He's busy dying (and/or cooking meth) -- he wants to sell his technology to a company which will do the licensing and/or litigating for him.
Even if it's "original inventor and heirs", you've created a liquidity process -- if you're a chemist with lung cancer, it would be great if you could sell your novel synthesis in order to pay for your cancer treatments rather than needing to start selling drugs yourself.
And then there's the problem of defining what a "practicing" entity is, of course. Someone who has at least one customer? Someone who has used the invention themselves? Someone who was planning on building a product, but didn't get into YC and ended up working at Microsoft instead while he tries to license his invention to raise money to pay for his next startup idea?