Better administrative controls, more fully fleshed out bot ecosystem, payments integration (perhaps by bot), ability to let users setup alerts (hashtag, keyword

Better administrative controls, more fully fleshed out bot ecosystem, payments integration (perhaps by bot), ability to let users setup alerts (hashtag, keyword or user) based on content in various chat spaces that they may or may not want to actively participate in, email integration, better binary document handling (attach files to chats), preferably with collaborative inline editing.... Just a few things OTOH. There are really two options, imho: 1) go after Slack & enterprise chat, or 2) go after Whatsapp, FB Messenger & WeChat and consumer group chat. If anyone creates a product that can do both, they'll be instant billionaires.