Will ubuntu phone os replace android os?

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http://askubuntu.com – I recently find out that Ubuntu would be released on some smartphones and though I would like to test drive this OS on my phone (which is a Samsung Galaxy nexus with Android jellybean 4.2.1) I would like to know if I could switch back to android at a later date as I love the interface. My phone model was used to demonstrate how Ubuntu functions so there shouldn't be a hardware mismatch. I know that dual booting on a mobile phone is a mere fantas and it would really help ifi knew whether or not Ubuntu would ruin alongside my handset's default is. (HowTos)