I disagree. Many nodes are important to support the network. It the 'decentralized' part. Few supernodes can easily be shutdown.
This might be a stupid idea, but what if part of all transaction fees went to a huge stockpile somewhere that was given out once a month randomly to someone who is forging. Then the incentive to run an open client would be the chance to win the 'Nxt lottery' that month. I know I'd be hard pressed to shut down my client and throw away my 'lottery ticket'.
Err, am I not sure I completely understand that incentive architecture. Could you rephrase it?
Basically, every time there's a transaction in the network, a fraction of the fee would be sent to a designated NXT account. If there's a lot of transactions this would add up to a nice amount over 30 days or so. Basically this would be awarded like a lottery every month to a random Nxter who ran an open client that month. The question is whether there's any way to verify if someone had been forging during the time period to be eligible. Maybe the reward would go out on a random day/time so that no one would know when it's coming and therefore be motivated to always be running an open client.
I'm just trying to think of ways to motivate people to forge when there's not much incentive to do so if you don't have a lot of stake.
This system would make forging akin to owning a lottery ticket. The odds would be somewhat low to win, but reward high enough to encourage participitation.