Current Rule: Current rules for trading of draft picks are:
During the Rookie Draft: Trades may involve rookie draft picks (including next year's), free agent and/or veteran players, and/or draft picks in the upcoming Free Agent Draft. (Rule 7.3.a)
During the Free Agent Draft: Trades may involve drafted rookies, next year's rookie picks, players under contract, and picks in the current Free Agent Draft. (Rule 7.3.b)
All other times: Nothing stated in the rules. In the past, I believe teams were allowed to trade rookie draft picks in the next two player drafts. For example, right now you could trade a rookie pick in both the 2017 and 2018 rookie drafts.
Proposed Rule Changes: Add to rules 7.1 "In-Season Trading", and 7.2 "Off-Season Trading" that trades draft picks are allowed for picks in next year's draft only.
Explanation: I'd like to get a rule on the books rather than rely on past precedent and having to search through the forums when it comes up. And I think the "next year's picks only" is reasonable as I'd like to avoid the situation of a team completely mortgaging their future or worse yet, quitting the league after trading all or nearly all their picks in the drafts in the second season.
I'm a little confused by the language of the rules as they are and your proposed change. Let me ask this: Suppose when trading opens this year that Team X trades this year's 2017 first round rookie draft pick and next year's 2018 first round rookie draft pick to Team Y for veteran QB Johnny Unitas. Would this trade be permitted given your amendment? Maybe some language clarification is needed (which is weird for me to suggest since I wrote the relevant rules. If even I'm confused, then the rules need a good edit).
As to the second issue (owners squandering their franchise future by trading away the farm), it did happen once during my term as Commissioner. As I recall, a new owner traded away multiple year's rookie picks to staff his team with veterans so he could win immediately. He won some games but didn't make the playoffs. Then he quit leaving a mediocre team with bad prospects. Try selling that to prospective replacement owners. I'm not sure how one would legislate against that behavior which is why I think we need to discuss your proposal in greater depth.
My proposed rule is you can only trade picks in the next rookie and free agent drafts to begin, all in real time.
So assuming we continue to hold the Rookie Draft before the Free Agent Draft:
During the Rookie Draft: Trades may involve picks in that rookie draft pick, picks in the current season's free agent and picks in the following season's rookie draft. So during the 2017 rookie draft you can trade 2017 rookie draft picks, 2017 free agent draft picks, and 2018 rookie draft picks. You cannot trade 2018 free agent draft picks during the 2017 rookie draft since the 2018 free agent draft is not the "next free agent draft to begin". The next free agent draft to begin is the 2017 free agent draft.
During the Free Agent Draft: Trades may involve drafted rookies, picks in the current free agent draft, picks in the following season's rookie draft and the following season's free agent draft. So during the 2017 free agent draft you can trade 2017 free agent draft picks, 2018 free agent draft picks, and 2018 rookie draft picks. You cannot trade 2019 picks since the "next drafts to begin" are the 2018 rookie and 2018 free agent drafts.
All other times: You can only trade picks in the next drafts to begin. So right now, you could trade picks in the 2017 rookie draft and the 2017 free agent draft, which are the next drafts to begin, but you cannot trade 2018 picks in either draft.