Speech recognition is not a replacement for the keyboard and mouse. In some circumstances it is a better input device than they keyboard/mouse but not an all. Speech recognition makes a terrible pointing device, just like the mouse makes a terrible text entry device, or the keyboard is bad for drawing. When speech recognition systems were first bolted onto the PC, it was thought that speaking menu names would be really useful. As it turns out, very few users use speech recognition to access a window menu because the mouse is much faster and easier.
Generally speaking, every feature in an application should be accessible from all input devices, keyboard, mouse, and speech recognition. Users will naturally use whichever input mechanism provides them the quickest or easiest access to the feature. The ideal input device for a feature will vary from user to user.