Headline (deceptive, please update) answer : Yes
Qualified answer, no.
Regardless of the "backwater bandwidth" endured in the farthest corners of the house, the "consumable" bandwidth will actually double. At the modem or MAC you have the potential to see 40Mb/s down. Further, peer to peer on the house network you should be seeing 100Mb/s for Cat5e and 1Gb/s on Cat6. If you have to share any broadcast domain (including WiFi) that will obviously degrade performance.
But no, if you are getting 1Mb/s now, that is a limit.
For Wifi, run ethernet to a second AP, and use high gain antennas, get rid of, and do not use repeaters, they are half duplex and extend range at a terrible cost to bandwidth. Find the clearest channel you can, your neighbours may be swamping you.
If these are workstations, consider WiFi to ethernet bridges, and place antennas at ceiling level.
If you can't do this,or can't run cable at a minimum use an external high gain antenna and place it/them high up.