It depends on the business. I worked at one company where we even kept roadmap information secret from the sales department, for fear that it would leak to cust

It depends on the business. I worked at one company where we even kept roadmap information secret from the sales department, for fear that it would leak to customers and stall current sales to customers who might just wait for the newer product if they knew the details. I think the defining characteristic may have been that these were big-ticket items: if you buy one, you're not going to buy another for a few years. On the other hand, at another one of my employers, a company selling enterprise software, it was much more important to maintain an ongoing relationship and to establish trust. That required more openness about future plans, to customers who buy a product, buy maintenance contracts, and keep buying more products, once they decided that we were a company that they could do business with in the long term.