AFAICS if the Austrians want to recover the capabilities they pruned out of the spec of their Typhoons their most cost-effective option would be to simply have a mid-life-upgrade to bring these aeroplanes up to the UK or German Tranche-1 spec. Replacing them with a new type has got to be the more expensive option.
But this is a classical example of the old adage about "Every pound you decide not to spend on initial procurement will cost you at least £10 over the service life..."
PDR