I think it will always be possible to sell your BIS, even if it's not supported by the state. I can always sign a contract saying "from now on I swear I'll give all my BIR to XXXX". It's basically a eternal debt contract, but your proposal makes this idea not so ridiculous.
"Worthwhile" is very relative. It all depends on your time preference regarding consumption.
Some people might prefer having 100 BIR right now rather than waiting 100 months. So they might accept to sell their BIS against 100 BIR.
More generally, some people might be more "carpe diem" oriented, so they'll just sell their BIS to people who think they'll live two hundred years (I'm exaggerating).
Interesting argument. I can't deny the possibility, but then things are not so different from nowadays, where people apply for a credit and then pay it back almost eternally, relative to their lifespan (30-years to repay your education loans, anyone?) So that's one way the system won't change at all

Private contracts do exist. And even if courts decided not to defend them, reality would, as screwed people would get angry and would use violence.
So, again like today, I guess. Sorry my system is not perfect

Ok, that's one thing. But can I be exempted from tax then?
You will be completely free to vote against any proposals for tax increase, campaign against them on blogs, and if you still run against a majority, then emigrate. Not so different than nowadays.
You can buy stocks with no more than a few dollars. That's a start. Maybe the OP has spent much more in contributions to the pirate party. Which to me is ironic.
LOL, I am the OP, and I've spent 50 EUR to pay my yearly membership fee. That's as much as I can give them.
I do not trade. I receive only dividends indeed.
Well, consider this: I did not steal those shares from this guy. I bought them. So in a sense, I rewarded him for the good work he's been doing. Without people like me, his job would have had much more difficulty to find a correct price in the market. I hope you can understand that.
Are you going to tell me that receiving money from doing nothing is fine as long as you don't pay to do that, but if you do that without stealing anyone, by investing wisely, it becomes morally wrong?
I didn't mean to morally judge you, just wanted to mention the existence of the argument against stocks. I do understand that the stock market provides a useful service (with the exception of high-frequency traders, them I do hold to be parasites on a system)
Still, to live on dividends, you do need a significant capital. What would 10 USD invested in stock bring your yearly as a ROI? A cent? ten, maybe? To survive on dividends you do need a substantial capital. I'm not going to ask you how much yours is, but you do agree with me that it must be at least a 5 digit figure with today's dividend rates. Such a sum would be unachievable for a lower-middle class person, even with hard work.