I am on the last update of lightroom 5 and tethered capture still does not work with el Capitan. is there any upgrade planned or do I have to buy the new lightroom 6?
Tethered shooting works fine with Lightroom 6.4 on El Capitan.
So you may go ahead and buy Lightroom and perform tethered shooting.
Adobe won't upgrade version 5. Like Tanuj says, if you need to tether, you'll have to get 6.4 or CC 2015.4 or later.