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I sent out mail a few months ago about the DITA TC considering moving the grammar files for MathML and SVG domains, either into the main area of the technicalContent profile, which will be separate from base DITA at 2.0, or into base DITA. The responses indicated that there may be some confusion about these domains, especially about the SVG domain.
It is not necessary to use the SVG domain in order to simply use SVG graphics in a DITA document. SVG images are rendered correctly by most online and print publishing engines. The only time a DITA implementation would need to use the SVG domain - and this usage would be by an implementer, not by an author - is if you need to manipulate those graphics in special ways. One example would be to adjust the dimensions of an image across different outputs because of different sizes in output device - if one output is for display on a phone, and another on a tablet, or a full-size computer monitor. In that case, I've had to use the SVG domain to access SVG elements and attributes within an SVG graphic to adjust the number of pixels in the output image.
For this reason, it's likely that we will keep the SVG and MathML domains within the technicalContent profile, even it we do move the grammar files around a bit within that profile. If, with full understanding of the usage of these domains, there is anyone who still thinks there are compelling reasons to move the SVG domain into base DITA, I'd be interested in hearing them.
[secretary, DITA Technical Committee]