Comcast (CMCSA) struck a cautious tone on mergers and acquisitions during its quarterly earnings call Thursday — but left the door open to future dealmaking once its planned Versant cable-network spin-off is complete. “We’ve said repeatedly, and I’ll say it again, that the bar is very high for us to pursue any M&A transactions given how strongly we feel about the businesses we have,” Michael Cavanagh, president of Comcast, said on the call. “That said, you should expect us to look at things [in and around ...