They are slowly disappearing. However they haven’t disappeared completely yet. The connection Wire with the Computer mouse is still there. Computer mouse will soon become wireless in future.
If that happens(and it will), then the name mouse should be changed. Because the reason behind such a name is the tail of a mouse. The wire which connects computer with computer mouse resembles with real mouse(living). The engineers who had designed and developed(invented) mouse, had noticed the similarity. They thought it looked like tail of a mouse. So they named the newly invented device mouse. From then this device is called mouse by the world.
Now it is the age of wireless devices. Wireless mouse is also available at the market now a days. We call them mouse with or without the tails.