"There goes the cellular neighborhood," he said.
Tim Ellis, real estate blogger at the Seattle Bubble, had similar concerns.
"All in all, I see this as another hit to the Seattle-area housing market," he wrote.
He interviewed a T-Mobile employee who indicated would put off plans to buy a house.
The T-Mobile manager said: "We have better than 20 percent saved and were looking to buy this fall, but now that won’t happen until I have a solid future with AT&T or somewhere else. There will certainly be workforce reductions at some point, but none of us have any idea how much."
Jon Talton, a pundit from The Seattle Times, also had a negative outlook. He said AT&T's merger with T-Mobile is a "big loss" for the local area.
"It will mean the elimination of an important corporate headquarters, as well as the end of thousands of well-paying jobs. The ones lost will be the high-end talent magnets. Also lost: The capital, prestige and power a headquarters brings," he writes of the $39 billion deal.
"The reality is that Seattle is growing fewer companies to last than it is losing them, and we're better off than most places. It's a huge challenge for economic-development leaders," he said.
AT&T has pledged to maintain a "large presence" in that area, but makes no promises about staffing levels.