Certainly plenty of people thought so at the time (including myself, as well as Microsoft's execs, or they wouldn't have done it), but although without the underhanded tactics they would have had a somewhat smaller market share and correspondingly smaller profit margins, in hindsight they would still have been the dominant platform vendor for desktops, office suites, and back office servers.
It turns out that Microsoft's strategy of sucking customers in with 'Better Together' all-MS integrated offerings, never making a customer have to consider another vendor because some custom in house software they rely on won't run anymore due to an upgrade (no matter how poorly), and as a distant second, introducing breaking changes for competing vendors' offerings wherever they could (eg. 'Windows isn't done until Lotus won't run', and even that tactic was eventually abandoned due to the overhead it introduced), was all they needed in order to maintain and grow their early lead.