According to news reports, Saudi Arabia has begun efforts to seek repatriation of antiquities from abroad. See: http://www.arabnews.com/?page=1§ion=0&article=118532&d=26&m=1&y=2009&pix=kingdom.jpg&category=Kingdom
The article is a bit unclear about the exact nature of the Kingdom's program, but hopefully any antiquities that are repatriated will not suffer the fate of buildings associated with the Prophet. These have been bulldozed in the past few years out of a new found fear that their continued existence would have promoted idolatry. See: http://www.independent.co.uk/news/world/middle-east/the-destruction-of-mecca-saudi-hardliners-are-wiping-out-their-own-heritage-501647.html
If Saudi religious authorities have such sway that they can order the destruction of Islamic buildings, can we really expect the Saudis to preserve pre-Islamic artifacts that may be characterized as idolatrous?