Shortcodes as Merge Tags

First convert your shortcode into a merge tag.

Shortcode: [gravityforms action="remaining" id="123" input_id="4.3" limit="100"] Merge Tag: {shortcode:gravityforms&action=remaining&id=123&input_id=4.3&limit=100}

Use your merge tag in as the default value in a field – or – in the GF conditional shortcode merge_tag parameter.

 [gravityforms action="conditional" merge_tag="{shortcode:gravityforms&action=remaining&id=123&input_id=4.3&limit=100}" condition="less_than" value="50"]
     Hurry! Only [gravityforms action="remaining" id="661" input_id="1.3" limit="100"] tickets left!
 [/gravityforms]