wait and see
lol. I'll be dead. I don't want to wait and see. But here are my 2 cents.
Who is in Mars that we need to communicate with? Darth Vader?
Light maybe 40% faster in vacuum but to go up to outer space and back has 2 factors to consider: latency and weather.
Finally, based on Shannon–Hartley theorem, bandwidth is limited to megabits for satellite transmissions. So, I am not sure if he knows what he is talking about. Powerful light beams? That is also subject to weather and clouds. It needs clear line of sight.
All I'd say is good luck. I won't be around if it ever happens at all, for sure.
Edit: One more thing. Bandwidth spectrum is a limited commodity.
I can appreciate your thoughts but trust me, it's not everyday that you get to challenge a man of his calibre. When he talks about technology and internet, he knows a thing or two(co-founded zip2 and paypal, remember?), when he talks about space, science and engineering he also seems to know a thing or two, being the founder, CEO and CTO of a private company who builds rockets for a living(and makes money out of it by delivering cargo for NASA) and at the same time being CEO of a company who builds probably the most advanced cars in the world. All this(and the satellite part) is actually part of a grand vision he has and through which he pushes step by step - to help speed up the advent of sustainable production and consumption of energy(in the case of cars) and advance civilization to a multi-planetary species(in the case of rockets).
So my suggestion would be to do your homework and see what this guys is really upto before you even think of laying out arguments against something you lack info of. He might really surprise you actually.
P.S. Here is an older yet interesting video worth the watch:
http://www.ted.com/talks/elon_musk_the_mind_behind_tesla_spacex_solarcity?language=enAnyway lets get back to NEM.
