After many months of activist-investor pressure, Monday’s abrupt departure of Twilio Chief Executive Jeff Lawson is a likely precursor to more change, such as a possible sale of its data and applications unit. Twilio’s shares TWLO, +6.68% soared almost 7% on Monday on the news that Lawson, who also co-founded the communications-software company, was stepping down. Last year, two activist investors — first Legion Partners and then Anson Funds — acquired stakes in the company, and have advocated for either a ...