How long do you think Voracek and G will be able to perform like they are now? 32?
http://alongtheboards.com/2015/09/peak-decline-elite-nhl-forwards/
32 would be a good bet in regards to continuing their current ~'peak' level production. (ie top 10-20 in the NHL in scoring)
34 would be a good bet in regards to them being above average 1st liners.
Though by the requirements I laid out in the article Voracek is kind of 'cusp' in regards to qualifying as an 'elite' forward. (though he would have 'just' made it due to having multiple 85+ point era adjusted seasons and a top 10 PPG and points finish.)
Though tbh in Giroux's case if he does not suffer many injuries going forward with the game he plays I could well imagine him doing a 'Sundin/Datsyuk/Sedin/Modano/Thornton' and still be an average to above average 1st line C at ~36.
Being a pass happy guy who is money on the PP and does not rely too much on physical gifts is kind of having all the ingredients to still excel even as he ages. (as assists decline slower than goals, and PP points are very sustainable into mid-30's... it is usually EV where there is a drop-off.)