St. Dominic's "last will and testament" was recorded in Peter of Ferrand's Legend, an adaptation of Bl. Jordan's Libellus with certain additional historical details.
"My very dear brothers," he said, "this is what I leave to you as a possession to be held by right of inheritance by you, my children. Have charity, preserve humility, and possess voluntary poverty." What a testament of peace, a testament never to be erased from the memory or modified by any later codicil.
There is a somewhat more expansive treatment of this theme here, which though treating of the same three bequests is of more doubtful provenance. (As the editor's note says, "Authorities have conflicting views on the authenticity, attribution, and utility of the document.")
...it is apparent that the founder of the Friars Preachers did not esteem poverty a whit less than his brother saint, the Seraphic Francis. But, unlike his saintly friend, he valued it principally as an effective means for the attainment of the ends of his apostolate. His attitude in this respect was based upon a twofold motive -- principle and expediency... As a matter of expediency, it was necessary that his followers be free from all incumbrances and the preoccupations which the possession of property entails, that they might enjoy a greater opportunity for study and possess the mobility necessary for the activities of their apostolate. Poverty, then, St. Dominic regarded as a means to an end; and if he expressed himself with the utmost vehemence in regard to those who should be unfaithful to its obligations, it was only because he foresaw that such infidelity meant the failure of their vocation as Friars Preachers. But he was farsighted enough to see that circumstances might arise which would render a rigorous observance of poverty a serious impediment to the work of saving souls, and he was broad-minded enough to meet this difficulty, as well as others of a similar nature, by placing in the hands of all superiors the constitutional power of dispensation.
It was said during his canonization process that, at the sight of some friars building on to a convent whose cells were so small they couldn't stand up straight in them, St. Dominic wept that they should so quickly abandon their vow of poverty:
At St. Nicholas, the cells of the brethren were quite plain and small. Therefore, Brother Ralph, the procurator, began to heighten some of them the length of an arm (Brother Dominic was away at the time). When Dominic returned and saw the higher cells, he began to weep; he rebuked Ralph and the other brethren many times, saying to them: "So soon you want to abandon poverty and build great palaces!" Hence, he ordered them to stop the work; it remained unfinished while he lived. As he himself loved poverty, so he loved to see it cherished by his brethren.
But that doesn't mean he would necessarily weep at the sight of the large, multi-story priories many of his sons and daughters now live in.
My guess is the first thing he'd ask is that his statues be moved out of sight.