That demand hasn't gone away, Armando Senra, BlackRock's head of iShares Americas, told CNBC's "ETF Edge" in an interview Monday. "You may have a little bit of a pullback in performance, but we continue to see the flows" into offerings such as the iShares U.S. Infrastructure ETF (IFRA) and the iShares Self-Driving EV and Tech ETF (IDRV), he said. "We're not just chasing one-year themes. We're looking for 10-year themes," Senra said, calling thematic investing "a long-term growth story for us and for the industry." While high-growth tech trades may take a back seat to value-based investments as the economic reopening gets underway, themes do have staying power, Salvatore Bruno, chief investment officer of IndexIQ, said in the same "ETF Edge" interview.