There're a few scenarios for the end of us. Tectonic and geologic activity is not one of them. In fact, tectonic plate movement and geologic activity is a healthy sign of planetary evolution - active planets are living planets. The worry is if there isn't such activity.
Our death is from one of the following;
1- The Sun will inflate into a stellar category Red Giant class IV and this will make it much hotter and will literally cook the planet. Eventually, the Sun will inflate so much, it'll consume Mercury, Venus, and Earth. It'll then puff out its exterior and what's left behind is an exotic nebula with a White Dwarf star in the middle. This will be the death of whole solar system. But that's not until for a looooooong time from today.
2- Near Earth Objects are an imminent danger. NEOs, comets, and Earth's orbit intersect more frequently than you think. If a substantially large object hits the planet, the planetary winter that follows will pretty much destroy life as we know it. There's hope however as this will trigger an Ice Age and when all the ash settles down; the Sun will still be there and bacteria (among other organisms) would have survived and will jump start life again.
3- Our Electromagnetic Shield is weakening. This is because the core of the Earth is slowing down for reasons we don't know. Historically, this has happened before over regular intervals. When Earth's core stops spinning, the Electromagnetic Field will vanish. When this happens; our protection from Coronal Mass Ejections and Solar Winds is consequently gone and this is bad news... very bad. CMEs and Solar Winds are highly radiative (mainly UV) and will pretty much kill everything. But even this is not the end of the planet; the core will start spinning again in the reverse direction and this will cause the planet to have a Geomagnetic Reversal; North and South will switch. The problem is that between the stop and go of the core's rotation we will be vulnerable to CMEs and that's the trouble.
4- There's also the religious scenario which doesn't convince me. So, I won't go into that...
Of those three scenarios, option 3 is most likely because we are due a Geomagnetic Reversal (last one occurred over 700,000 years ago) and an increase in tectonic and geological activity is an associate of the reversal.
Sorry I had to turn my nerd on, but you asked for it.
Oh, and yes you will get to see me before the Mayan Calendar ends (not that I believe in it to begin with).. If all goes well, I should be visiting between next year and 2012 at the very latest!