If you want to still keep whittling away at PHP code, then don't do anything.

You want to learn new languages and tools because you enjoy your job. At least I hope you do - you do this 8 hours a day.

I've worked with guys who were 20 years into their career and only knew PHP (ok ok and some C) and haven't even heard of SVN let alone something modern like Git or Mercurial. "Source Control, what's that?"

You don't want to become one of those guys when you're 50. Suddenly your job is precarious and worse than that, if you should lose your job where will you find other work?