This does appear to be a potential conflict of interest.
One approach is to make the Bitcoin blocksize larger and adapt it through a fork to process more transactions by itself.
The other is to implement Bitcoin features through the use of sidechains but keep the max size the same for now in effect creating a system of Altcoins that are perfectly intergrated with Bitcoin also known as sidechains and thus becoming a true part of Bitcoin.
If this becomes a question of Bitcoin development then discussion should be moved towards what the majority of users would prefer to have, one option would be to fork with the potential to improve Bitcoin through intergration into sidechains or to fork and increase the blocksize for now, my main question is why a bigger transaction size would interfere with the blockstream idea in the first place and why both couldn't be done in one fork.
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"The implementation of lightning networks would also require appropriate tweaks to Bitcoin core. Some developers have noted that there is a certain degree of affinity between sidechains and lightning networks.
The deployment of sidechains interoperable with Bitcoin requires the implementation of suitable hooks in Bitcoin Core. That will inevitably take some time, but it’s worth noting that some Blockstream team members are also Bitcoin Core developers.
The Bitcoin Sidechains paper envisages an ecosystem of “sidechains” separate from the main Bitcoin blockchain but interoperable with it. A sidechain can carry bitcoin as currency, in which case users will be able to seamlessly transfer bitcoin between the sidechain and the main blockchain. At the same time, the sidechain can implement changes from Bitcoin Core. For example, a sidechain can implement more powerful scripting features or more watertight privacy.
“Other approaches seek to modify Bitcoin protocols in various ways,” wrote Robert McGrath. “For example, Sidechains aim to create alternative blockchains hanging off the main blockchain, which would help limit the costs of the main blockchain. Another variant is the Lightning network, which aims to allow some transactions to be performed “on the side,” and on send the results to the main blockchain.”
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We can have a network of arbitrarily complicated transactions, such that they aren’t on the blockchain (and thus are fast, cheap and extremely scalable), but at every point are ready to be dropped onto the blockchain for resolution if there’s a problem,” he said. “This is genuinely revolutionary.”
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If we use the sidechains without increasing the block size in BTC, the sidechains will also fill up our disk.
If I read the above quote correctly Eastwind it would send a message to the Blockchain but the sidechain would have its own client and do the work external to the main chain in most cases, instead we would see a shift of weight in the sense that Bitcoin is used as a ledger to track and record transactions with complex instruments moved off the blockchain with the results recorded on the main ledger. It also would be possible to have merged mining supplement Bitcoin fees and blocks based on the presumption that Sidechains have their own value in and of themselves.
In other words an interesting article when you consider some of the implications of it.
https://bitcoinmagazine.com/20618/blockstream-starts-development-lightning-network/