My thoughts on this idea can best be summed up in the immortal words of Margaret Thatcher: "No. No. No." :)
Just because something has outdated visual effects is not a good reason to remake it. Yes, the shark looks rubbery in a couple of shots, but I'll take rubbery shark over rubbish CGI any day of the week and twice on Sundays. Plus any modern remake would almost certainly not be shot on location at sea, which is a significant part of what makes the original so brine-under-the-fingernails brilliant.
Also, one does not "modify" the Jaws theme. That is outright blasphemy against the greatest composer of our age, John Williams.
Jaws is perfect as it is. I'm not completely anti-remake (see my article below for why) but any remake of Jaws would be the work of the antichrist.