The bread and butter of the ETF industry may be sector plays, but managers would like to reach out to a broader audience. The debut of life-cycle ETFs, fund of fund ETFs and active ETFs are squarely aimed at the longer-term investor. A two-fold question remains: Will audiences be ready for the new fleet of funds, and will popular existing funds become too big for their britches? The anemic interest in the new actively managed funds seems to be a sign that it will take time for these funds to catch on. The Dent Tactical ETF ( DENT), a recently launched active fund, has an average daily trading volume of less than 7,000 shares. Investors who are turning to ETFs out of distrust for active managers may find active ETFs hard to swallow. Concerns over size should not be discounted. New regulation from the Commodities Futures Trading Commission has sent ETFs like United States Natural Gas ( UNG) and PowerShares DB Commodity ( DBC) scurrying to stay within position limits. As these funds grow ever larger, there may be further limitations for futures-based commodity ETFs. Despite the setbacks that have challenged the relatively new industry, it seems as though we are directly situated in an ETF boom. As ETFs continue to grow, and attempt to be everything to every investor, the evolution will be remarkable to watch. -- Written by Don Dion in Williamstown, Mass.