Then you have nothing to worry about.
However I think you should keep in mind the "domino effect" that can occur when your nearest & dearest takes a step forward.
Cast your mind back to 07, when you were granted planning permission it cast huge doubts over our project, the added dimension of having another stadium (appear) to be built just around the corner makes a scheme with "hurdles" seem almost insurmountable. Fans jump on the "your screwed bandwagon", which leads to the media taking the same stance (as we all know how lazy some journalists are). Sponsors become harder to come by, players become reluctant to sign long deals- the problem is exasperated in many ways.
Before you know it the whole RL community is casting doubt over your viability as a SL club.
All of what you saw (and some reveled in) could very well happen to Castleford SHOULD Newmarket get the nod.
Quick question (& answer honestly) do you see 2 stadiums being built?
Most, myself included, have maintained that only 1 stadium will ever be built, would you say you subscribe to this notion?
Newmarket is far from sorted & has never been plain sailing, but as I see things there are a lot less problems to overcome.