Hi Bill,
Once in the Support Group you would continue to be in receipt of Contributory ESA long-term. This would only change if you were reassessed and allocated to the WRAG, in which case it would be limited to 365 days payment.
To summarise. You can remain on Contributory ESA in the Support Group for life as long as you are considered to still meet the Support Group descriptors.
Nothing on this board constitutes legal advice - always consult a professional about specific problems