SVG is an open standard, developed by W3C. I really don't see it dying any time soon. Just because certain companies decide to drop its use for their commercial products (usually because they need, or feel they need, something more customised), it does not at all mean SVG will disappear on a more global scale.
At the moment, it's undoubtedly the most widely used vector graphics format on the web. Just take for example the images on Wikipedia - for almost all diagrams SVG is either used or there is a notice stating that it should be used. Many other open source projects endorse it in a similar way.
Now, the XAML markup language (part of WPF/Silverligtht) has been seen as a competitor to SVG by some, but truly they only overlap in functionality to a certain degree. (XAML supports lots of other things such as data binding, events, triggers, etc.) Indeed, the general use of XML is much restricted in that browsers don't natively support it (and can't properly, because of the fact that it's tightly bound to MS technologies). I would not even believe that it's strictly a direct competitor to SVG, nor that Microsoft have intended so.
To conclude, I don't think one can envisage SVG dying out until something clearly improved (and open-standard) comes along to replace it. As far as I know, there is nothing like that at the moment.