If multi channels need to close at same time it could a major problem due to the 7 transaction per sec onchain limit.
How likely would such a problem be? The problem is this: a single blockchain will simply not scale to the degree necessary for mass adoption without a) massive centralization or b) a mesh network on top of the blockchain such as the Lightning Network or the Raiden Network (to be used with Ethereum). It is possible, however, to utilize atomic cross-chain swaps. But then we're talking about multiple blockchains.
Additionally, LN is not being used and not even ready. It could be 1-2 years before the average Bitcoiner can use it with a friendly user experience. Again, the public does care about ideology, they just want a product that looks and feels easy to use. Bitcoin so far is still very un-user friendly and does not scale. The core team has shown many times they don't care about user friendly or practical use. Its all about their ideology - them and not the user experience.
Sure, the LN and other similar solutions not ready for production. But they are not ready for any coin. User friendliness is more a property of wallets and not the underlying blockchain.
Which coin are you a proponent of?
Due to Bitcoin size and liquidity its def not going anywhere any time soon. I do think over time protocols that can self fund, self govern, market themselves, develop killer features and build big equitable communities behind them will go very far. There's so many economic incentives and features a blockchain needs to have to be truly successful. A lot of Bitcoin's future success will rely on scaling the problem of mining centralization. One of the main hurdles holding back coins like Dash and NEO is lack of big fiat exchange support. It was only until last year ETH got added to any fiat exchanges and only this summer before Asia adding ETH/fiat trading pairs. The decentralized exchange protocols could really change the game in liquidity and accessibility + the peer to peer fiat options under development. Once we see better ease of use crypto should really take off in developing world.
I agree about what you say about decentralized exchanges and the developing world.
But I still maintain that no single blockchain will ever be able to scale to the level necessary for mass adoption without very heavy mining centralization. I'd say decentralized exchanges and atomic swaps between chains in addition to mesh networks such as the Lightning Network are required for mass adoption. The value of Bitcoin may rise to the tens of hundreds of thousands per coin only if becomes generally accepted as a digital store of value ("digital gold").
I think for payments Dash will win a big market share because they are building an entire eco-system for a mass appealing payments platform. https://smartcash.cc/ is also very interesting.