As a former Vikings fan, I have followed Randy's career since he first arrived in Minnesota.
By what I've seen with him in his financial dealings, as long as the Patriots treat him fairly and give him market value, he'll return and most likely retire as a Patriot.
He didn't hold out his rookie season (he easily could have as he was slated to be a top 10 pick); in fact he signed his rookie deal just hours before signing in for training camp and traveled with Cris Carter to Mankato to begin training camp.
In the summer of 2000, his 3rd season, he briefly, through an intermediary, complained about his deal (I think he was slated to receive around 500K that year in base salary) that he wanted a new deal and suggested he may skip some training camp, but it never came to fruition and he arrived on time.
Now I don't think you are going to get him 'on the cheap', but Randy has not demonstated to be greedy (like a TO) when it comes to his contract.
He cares about winning more than anything, I don't see any way Randy doesn't retire a Patriot as long as Brady and Belichick are there, and the organization gives him a fair and market-value deal.