Cardano is pushing strong for NFT authors, some collectibles found on there are really cutesy-wutesy and imVho will have a nice future once cardano implements smart contracts.
There's the Crypto Doggies - where 50% of income from doggo sales go to actual dog charities, and Nifty Teddies - where 5% of the drop incomes go to bear conservation funds.
Needless to say htey're super cute and expected to soon become actors in blockchain games.

how can a coin be killed? please, enlighten me. i'd really like to kill a couple (hundreds), so i could really use the info. for the benefit of all cryptocurrencies.

seriously:
burst is very alive and a new roadmap is out - allegedly with the dymaxion it. that much on the topic of "killing".
PoC Consortium cheated on nobody - the burst community simply decided to not like the aspera wallet license, and the PoC Consortium heard the community opposition and moved on: https://www.reddit.com/r/burstcoin/comments/a6o592/i_do_not_support_aspera/ and gave significant resources to the BMF (burstcoin.ist, burstwiki) and still keeps operating the explorer and helping the BATs get in touch with exchanges.

as for helix, you might want to check out the reasons why it is a closed source software that comes with a license that has to be paid: because the R&D costs, and even with the license price, it is still the cheapest TB one can buy for PoC mining - which will significantly level the playground, especially between the ~PB and smaller (50-100 TB) miners.

really?
what i know is that they tried to launch their national crypto the petro twice, and failed both times. the last i've readon the subject was that they were forcing the usage of crypto in some instances (pensions and such), but the petro still hasn't become the national currency.

what's the difference between a coin and a token?
and no - if there is an off-chain collateral, be it gold, any other commodity, or fiat, such as with other stablecoins (USDT, PAX, etc), there's no way to decentralize them.

There is a fully gold-backed stablecoin, called Digix. It is regularly audited, and the gold backing the coin is redeemable from the issuer. The problem with it is that it's, just like any off-chain collateralized crypto, fully centralized.
I've written a series of articles about stablcoins, part 2 was this: https://medium.com/datadriveninvestor/gold-on-a-block-stablecoins-part-2-7928598b282d

i'd say it's quite important. it may happen that the usage of the chain at the very beginning is not high i.e. that the capacity is unused, but it helps (by means of not limiting) development of dApps and implementation for usecases other than payments. e.g. a chain with high tps can be used for data storage, IoT type of data storage, different data tracking. on the other hand, high tps implementation from the very start will help the code dev team to focus on implementation of other features, instead of constantly increasing the transaction throughput as the usage of the coin grows.