You mean Mathematica competitors? It depends what you mean by “major”. If we don’t do anything really stupid, I think it’s unlikely anyone else will reach a million users in the foreseeable future. But the more successful we are, the more there’ll be people who’ll want to claim that they’re building systems that are like ours. There’s certainly nothing impossible about building something like Mathematica—after all, we’ve done it. But it’ll take a great deal of effort, and I very much doubt the marketplace would be all that interested.