Nokia has big plans for all three of its platforms. Despite the huge growth of affordable smartphones, the S40 platform will go on, getting touchscreens, dual-SIM and QWERTY keyboards, while Symbian and Maemo will get new interfaces with improved speed and multi-touch.
Nokia sees Maemo taking up a big portion of the number of devices sold by 2011, compared to the current niche status of the platform. When Maemo 6 hits it will bring along multi-touch support as well. Both Maemo and Symbian will get new interfaces in 2010 - Symbian^1 should be out in the first half of 2010 and Symbian^2 by the end of 2010.
As for Series 40, there have been attempts to make an S40 handset with a QWERTY keyboard but that didn't catch on. Touchscreens and dual-SIM phones is breaking new ground for Series 40.
These new and improved S40 devices will begin appearing in 2010 along with the new Symbian and Maemo devices. Nokia maintains that Symbian is their smartphone platform of choice, keeping Maemo to high-end "mobile computers". S40 is here to stay as well according to Nokia's strategy - multiple platforms to cover all the market segments for mobile phones, instead of stretching one platform from the low end to the high end.
A new interface for Symbian sounds great (the S60 5th edition specifically needs a lot of attention), but for S40 they say in 2010 they will "bring touch interaction on top of Series 40's recently renewed user interface". That sounds a lot like what the touch-enabled Symbian was at first (and arguably still is) - a non-touch UI with touch capabilities added.
That may be an oxymoron, but S60 was designed to be operated with a keypad, so merely adding touch capabilities resulted in a subpar touchscreen experience, which attracted a lot of criticism.