You're more likely to see tinkering at the edges, like the move to DVD navigation, changed door mirrors, 7 speed transmission. That said, the R107 was around for 17 years, the R129 for 12 and the R230 came out in Germany in 2001, so it's about to enter its 4th year. If you think an all new SL will come out after 10 years, that would suggest a mid-life makeover in 2 years but I would be surprised if it was substantial, few would say the car needs it yet. Look at the S class and CL which are some years older - very few changes although the S will be replaced by a butt-ugly Maybach wannabee in the next couple of years. The CL is said to get sharper styling. The SLK and CLK were entrants into new market segments and you could argue that both of thoese were ripe for an earlier makeover.