My Fiancée would not be entering the UK on a 10 year path . . .
She would enter on a Fiancée Visa !
I would be placed on a 10 year path if something unexpected should occur within the 1-5 years and unable to meet Financial requirements!
Exactly - physicskate was just clarifying that point, as it is not possible to enter the UK on the 10-year path anyway. The 10-year path is only available to people ALREADY living in the UK and applying to extend their current visa... but can't meet the requirements for that visa.
Either way though, it makes no difference. She will still be eligible for the NHS because her visa will be valid for more than 6 months.
I'm sure you're aware though, that the 10-year path isn't a 'get out' or 'easy way out' of the financial requirements - it's an exceptional circumstances visa that prevents families from being split up (due to the 'right to family life') when technically the visa holder doesn't actually qualify to stay in the UK.
It's not something you should go into the fiance visa expecting to be put onto because you don't think you will meet the requirements in 6 months or in 2.5 years... you should try to qualify for the financial requirement if at all possible, doing everything in your power over the first 2.5 years to make sure you can qualify for it. If something unexpected happens and you find that despite your best efforts, you simply can't meet the requirement, you may be transferred to the 10-year path if you prove you meet the requirements to stay in the UK under Article 8, the right to family life.
Remember also that once your wife has her FLR(M) visa, she can work in the UK (if she is able to work) and if she is earning £18,600 in 2.5 years' time then you could still meet the requirements on the 5-year path, even if you lose your benefits.