Lightning network is the only thing that Bitcoin needs right now. Once that is in place, there is no need to implement other altcoins because of them not having any 'advantage' over Bitcoin anymore. The only thing altcoins do better than Bitcoin right now, is offering faster confirmation times, and that for a lower price. I however have to point out that this is mainly the result of lacking altcoin usage. As soon as whatever altcoin sees its usage grow exponentially, like what happened with Ethereum for example, then they will suffer from network cluttering as well, which results in higher fees. I just can't say anything about when lightning network gets activated. I wish as soon as possible, but without it being tested through properly, it won't be launched.