When this type of issue arises, the best way it to decide and evaluate which of your clients will be good candidates for training online. Some will be ok with it, others they prefer a personal training in-person. Also, can you trust them in following your directions and work out postings? I would stick with Skype since it’s the next best option to in-person training. Email is a good alternative as well, but then you have no way of knowing if they did what they were supposed to do and in the correct form. The other option is to sell your business or contacts and start fresh where ever you are moving too.